99 results on '"Tasinato N."'
Search Results
2. Probing the existence of phase transitions in one-dimensional fluids of penetrable particles
- Author
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Prestipino, S., Gazzillo, D., and Tasinato, N.
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Condensed Matter - Soft Condensed Matter - Abstract
Phase transitions in one-dimensional classical fluids are usually ruled out by making appeal to van Hove's theorem. A way to circumvent the conclusions of the theorem is to consider an interparticle potential that is everywhere bounded. Such is the case of, {\it e.g.}, the generalized exponential model of index 4 (GEM-4 potential), which in three dimensions gives a reasonable description of the effective repulsion between flexible dendrimers in a solution. An extensive Monte Carlo simulation of the one-dimensional GEM-4 model [S. Prestipino, {\em Phys. Rev. E} {\bf 90}, 042306 (2014)] has recently provided evidence of an infinite sequence of low-temperature cluster phases, however also suggesting that upon pushing the simulation forward what seemed a true transition may eventually prove to be only a sharp crossover. We hereby investigate this problem theoretically, by three different and increasingly sophisticated approaches ({\it i.e.}, a mean-field theory, the transfer matrix of a lattice model of clusters, and the exact treatment of a system of point clusters in the continuum), to conclude that the alleged transitions of the one-dimensional GEM4 system are likely just crossovers., Comment: 18 pages, 9 figures
- Published
- 2015
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3. Erratum: The Italian national project of astrobiology-life in space-origin, presence, persistence of life in space, from molecules to extremophiles (Astrobiology (2020) 20:5 (580-582) DOI: 10.1089/ast.2020.2247)
- Author
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Onofri S., Balucani N., Barone V., Benedetti P., Billi D., Balbi A., Brucato J. R., Cobucci-Ponzano B., Costanzo G., Rocca N. L., Moracci M., Saladino R., Vladilo G., Albertini N., Battistuzzi M., Bloino J., Botta L., Casavecchia P., Cassaro A., Claudi R., Cocola L., Coduti A., Di Donato P., Di Mauro E., Dore L., Falcinelli S., Fulle M., Ivanovski S., Lombardi A., Mancini G., Maris M., Maurelli L., Murante G., Negri R., Pacelli C., Pagano I., Piccinino D., Poletto L., Prantera G., Puzzarini C., Rampino S., Ripa C., Rosi M., Sanna M., Selbmann L., Silva L., Skouteris D., Strazzulli A., Tasinato N., Timperio A. M., Tozzi A., Tozzi G. P., Trainotti L., Ugliengo P., Vaccaro L., Zucconi L., Onofri S., Balucani N., Barone V., Benedetti P., Billi D., Balbi A., Brucato J.R., Cobucci-Ponzano B., Costanzo G., Rocca N.L., Moracci M., Saladino R., Vladilo G., Albertini N., Battistuzzi M., Bloino J., Botta L., Casavecchia P., Cassaro A., Claudi R., Cocola L., Coduti A., Di Donato P., Di Mauro E., Dore L., Falcinelli S., Fulle M., Ivanovski S., Lombardi A., Mancini G., Maris M., Maurelli L., Murante G., Negri R., Pacelli C., Pagano I., Piccinino D., Poletto L., Prantera G., Puzzarini C., Rampino S., Ripa C., Rosi M., Sanna M., Selbmann L., Silva L., Skouteris D., Strazzulli A., Tasinato N., Timperio A.M., Tozzi A., Tozzi G.P., Trainotti L., Ugliengo P., Vaccaro L., Zucconi L., Onofri, S., Balucani, N., Barone, V., Benedetti, P., Billi, D., Balbi, A., Brucato, J. R., Cobucci-Ponzano, B., Costanzo, G., Rocca, N. L., Moracci, M., Saladino, R., Vladilo, G., Albertini, N., Battistuzzi, M., Bloino, J., Botta, L., Casavecchia, P., Cassaro, A., Claudi, R., Cocola, L., Coduti, A., Di Donato, P., Di Mauro, E., Dore, L., Falcinelli, S., Fulle, M., Ivanovski, S., Lombardi, A., Mancini, G., Maris, M., Maurelli, L., Murante, G., Negri, R., Pacelli, C., Pagano, I., Piccinino, D., Poletto, L., Prantera, G., Puzzarini, C., Rampino, S., Ripa, C., Rosi, M., Sanna, M., Selbmann, L., Silva, L., Skouteris, D., Strazzulli, A., Tasinato, N., Timperio, A. M., Tozzi, A., Tozzi, G. P., Trainotti, L., Ugliengo, P., Vaccaro, L., and Zucconi, L.
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life in space-origin ,astrobiology ,persistence of life in space ,from molecules to extremophiles in space ,Settore CHIM/02 - Chimica Fisica - Abstract
The Italian National Project of Astrobiology―Life in Space―Origin, Presence, Persistence of Life in Space, from Molecules to Extremophiles A member’s name should be added to the OPPS Project Team: Stavro Ivanovski on page 580 footnotes. We have made this correction on the title page of the article and the eTOC.
- Published
- 2020
4. ATIRS package: A program suite for the rovibrational analysis of infrared spectra of asymmetric top molecules
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Tasinato, N., Pietropolli Charmet, A., and Stoppa, P.
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- 2007
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5. Virtual Reality bridge between Chemistry and Cultural Heritage: the “Sala degli Stemmi” Case Study.
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Martino, M, primary, Lazzari, F, additional, Tasinato, N, additional, and Barone, V, additional
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- 2020
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6. FTIR spectrum of vinyl fluoride near 3.6 μm: rovibrational analysis of the ν4+ν7 band and modelling Coriolis resonances in a seven-level polyad
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Stoppa, P., primary, De Lorenzi, A., additional, Pietropolli Charmet, A., additional, Giorgianni, S., additional, Tasinato, N., additional, and Gambi, A., additional
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- 2018
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7. High resolution FTIR spectroscopy of chlorofluoromethane near 13 micrometri: rovibrational analysis and resonances of nu5 and 2nu6 bands in CH235ClF and CH237ClF
- Author
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Stoppa P., Baldacci A., Pietroplli Charmet A., Tasinato N., Giorgianni S., CANE', ELISABETTA, NIVELLINI, GIAN DOMENICO, Stoppa P., Baldacci A., Pietroplli Charmet A., Tasinato N., Giorgianni S., Canè E., and Nivellini G.
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FTIR spectroscopy ,chlorofluoromethane - Abstract
The FTIR spectra of CH2ClF (natural isotopic mixture) and CH37 2 ClF (isotopically enriched sample) were investigated in the 5 and 26 region between 700 and 800 cm1 at a resolution of 0.004 cm1. The 5 and 26 vibrations of A0 symmetry give rise to a/b hybrid bands with a very predominant a-type component. Due to the proximity of their band origins, the v5¼1 and v6¼2 levels perturb each other by Fermi and Coriolis resonances. The interaction mechanisms, previously investigated in the rotational spectra of CH35 2 ClF, were extended to the less abundant isotopic species CH37 2 ClF and to higher J and Ka values in the main isotopologue. The spectral analysis resulted in the identification of 4188 and 5392 transitions for CH35 2 ClF and CH37 2 ClF, respectively. All the assigned data were simultaneously fitted using the Watson’s A-reduction Hamiltonian in the Ir representation and perturbation operators. Excited state parameters, band origins and coupling terms for the 5/26 dyad of both isotopologues were determined.
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- 2013
8. FTIR spectrum of vinyl fluoride near 3.6 μm: rovibrational analysis of the ν4+ν7 band and modelling Coriolis resonances in a seven-level polyad.
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Stoppa, P., De Lorenzi, A., Pietropolli Charmet, A., Giorgianni, S., Tasinato, N., and Gambi, A.
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FLUOROETHYLENE ,CHEMICAL reduction ,COUPLING reactions (Chemistry) ,PHOTOLYSIS (Chemistry) ,FOURIER transform infrared spectroscopy ,SYNTHETIC gums & resins - Abstract
The Fourier transform infrared (FTIR) spectrum of vinyl fluoride, H
2 C=CHF, has been widely investigated in the region of the ν4 +ν7 combination band around 2800 cm−1 at a resolution of 0.005 cm−1 . This vibration of A' symmetry gives rise to an a/b-hybrid band with a predominant a-type component. The rovibrational structure is strongly perturbed and the analysis has been rather complicated since this combination band is involved at least in a seven-level interacting polyad, including the ν8 +2ν10 , 2ν8 +ν10 , 2ν7 +ν9 , ν7 +ν8 +ν12 , ν5 +ν9 +ν10 and ν7 +ν10 +ν12 vibrational states. The study has been further complicated by the absence of transitions coming from the perturbers that were considered as dark states. The spectral analysis resulted in the identification of 936 transitions with J" ≤ 46 and Ka " ≤ 11, all belonging to the a-type component. Most of the assigned data have been fitted using the Watson's A-reduction Hamiltonian in the Ir representation and proper Coriolis perturbation operators. The model employed includes seven different resonances within a complex polyad resonant system and a set of spectroscopic constants for the ν4 +ν7 combination band, for the dark states, and Coriolis coupling coefficients have been determined. [ABSTRACT FROM AUTHOR]- Published
- 2018
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9. High-resolution FTIR spectroscopy of HCFC-31 in the 950−1160 cm−1region: rovibrational analysis and resonances in the ν4, ν9and ν5+ν6bands of CH235ClF
- Author
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Stoppa, P., primary, Baldacci, A., additional, Tasinato, N., additional, Charmet, A. Pietropolli, additional, Giorgianni, S., additional, Tamassia, F., additional, Cané, E., additional, and Villa, M., additional
- Published
- 2015
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10. Spectroscopic meaurements of SO2 line parameters in the 9.2 micrometer atmospheric region and theoretical determination of self-broadening coefficients
- Author
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Tasinato, N., Pietropolli Charmet, A., Stoppa, P., Giorgianni, S., and Buffa, G.
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- 2010
11. Spectroscopic measurements of SO2 line parameters in the 9.2 θm atmospheric region and theoretical determination of self-broadening coefficients
- Author
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Tasinato N., Pietropolli Charmet A., Stoppa P., Giorgianni S., and Buffa G.
- Subjects
atmospheric chemistry ,spectral line broadening ,infrared spectra ,sulphur compounds ,vibrational states - Abstract
N.A.
- Published
- 2010
12. High-resolution infrared spectroscopy of CH281BrF near 8 μm: rovibrational analysis of the ν3 and ν8 fundamentals and resonances with the dark states 2ν5 and ν6 + ν9
- Author
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Stoppa, P., primary, Tasinato, N., additional, Baldacci, A., additional, Pietropolli Charmet, A., additional, Giorgianni, S., additional, and Wugt Larsen, R., additional
- Published
- 2013
- Full Text
- View/download PDF
13. High-resolution FTIR spectroscopy of HCFC-31 in the 950−1160 cm region: rovibrational analysis and resonances in the ν 4 , ν 9 and ν 5 +ν 6 bands of CH 2 ClF.
- Author
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Stoppa, P., Baldacci, A., Tasinato, N., Charmet, A. Pietropolli, Giorgianni, S., Tamassia, F., Cané, E., and Villa, M.
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CHLOROFLUOROMETHANE ,RESONANCE ,NATURAL isotopic abundance ,CORIOLIS force ,FOURIER transform infrared spectroscopy ,HAMILTONIAN systems - Abstract
The FTIR spectrum of CH2ClF (natural isotopic mixture) was investigated in the ν4, ν9 and ν5+ν6 band region between 950 and 1160 cm−1at the resolution of 0.004 cm−1. The ν4and ν5+ν6 vibrations of A′ symmetry give rise toa/bhybrid bands with a predominanta-type component. The ν9vibration of A″symmetry, expected with ac-type band contour, shows an intense Coriolis-induced parallel component (ΔKa= 0, ΔKc= 0) derived from mixing with thev4= 1 vibrational state. The high-resolution spectra of ν9and ν5+ν6 have been analyzed for the first time, while the assignments of the ν4band, previously investigated, have been extended to higherJandKavalues in theb-type component. The spectral analysis resulted in the identification of 1508, 809 and 349 transitions for the ν4, ν9and ν5+ν6 bands of CH235ClF, respectively. Besides the strong first-ordera-andb-type Coriolis resonances between ν4and ν9, the ν5+ν6 vibration was found to interact through ac-type Coriolis with the ν4and 3ν6. High-order anharmonic resonance (ΔKa= ±2) between ν4and ν5+ν6 was also established. All the assigned data were simultaneously fitted using the Watson's A-reduction Hamiltonian in theIrrepresentation and the relevant perturbation operators. The model employed includes five types of resonances within the tetrad ν4/ν9/ν5+ν6/3ν6. Α set of spectroscopic constants for ν4, ν9and ν5+ν6bands as well as parameters for the dark state 3ν6and seven coupling terms have been determined. The simulations performed in different spectral regions satisfactorily reproduce the experimental data. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
14. High resolution FTIR spectroscopy of chlorofluoromethane near 13 µm: rovibrational analysis and resonances of ν5and 2ν6bands in ClF and ClF
- Author
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Stoppa, P., primary, Baldacci, A., additional, Charmet, A. Pietropolli, additional, Tasinato, N., additional, Giorgianni, S., additional, Cané, E., additional, and Nivellini, G., additional
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- 2012
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15. Jet-cooled diode laser spectrum and FTIR integrated band intensities of CF3Br: rovibrational analysis of 2ν5and ν2 + ν3bands near 9 μm and cross-section measurements in the 450–2500 cm−1region
- Author
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Pietropolli Charmet, A., primary, Tasinato, N., additional, Stoppa, P., additional, Baldacci, A., additional, and Giorgianni, S., additional
- Published
- 2008
- Full Text
- View/download PDF
16. High-resolution infrared spectroscopy of CH 2 BrF near 8 μm: rovibrational analysis of the ν 3 and ν 8 fundamentals and resonances with the dark states 2 ν 5 and ν 6 + ν 9.
- Author
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Stoppa, P., Tasinato, N., Baldacci, A., Pietropolli Charmet, A., Giorgianni, S., and Wugt Larsen, R.
- Subjects
- *
CARBENES , *INFRARED spectroscopy , *VIBRATIONAL spectra , *DARK states (Quantum optics) , *ENERGY bands , *SYMMETRY (Physics) - Abstract
The infrared spectrum of isotopically enriched CH281BrF was investigated in the ν3and ν8region between 1150 and 1370 cm−1at a resolution of 0.003 cm−1. The ν3vibration of symmetry species A′gives rise to ana-/b-hybrid band witha-type predominance, while the ν8mode of A″symmetry producesc-type absorption. Due to the proximity of the band origins to those of closely lying overtones and combination bands, thev3= 1 andv8= 1 levels were found perturbed through Coriolis resonance by thev5= 2 (A′) andv6=v9= 1 (A″) states, respectively. The spectral analysis resulted in the identification of 3132 transitions (J″≤ 98 andKa″≤ 14) for the ν3and 2958 transitions (J″≤ 68 andKa″≤ 19) for the ν8bands. The assigned data were fitted using the Watson's A-reduction Hamiltonian in the Irrepresentation and the perturbation operators. Although no transitions belonging to the perturbers were observed, the band origins and excited state parameters for fundamentals and ‘dark states’ together with coupling terms for the ν3/2ν5and ν8/ν6+ ν9dyads were determined. [ABSTRACT FROM AUTHOR]
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- 2014
- Full Text
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17. High resolution FTIR spectroscopy of chlorofluoromethane near 13 µm: rovibrational analysis and resonances of ν 5 and 2 ν 6 bands in ClF and ClF.
- Author
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Stoppa, P., Baldacci, A., Charmet, A. Pietropolli, Tasinato, N., Giorgianni, S., Cané, E., and Nivellini, G.
- Subjects
CHLOROFLUOROMETHANE ,VIBRATION (Mechanics) ,MIXTURES ,SYMMETRY (Physics) ,ISOTOPOLOGUES ,FOURIER transform infrared spectroscopy - Abstract
The FTIR spectra of CH2ClF (natural isotopic mixture) andClF (isotopically enriched sample) were investigated in the ν5and 2ν6region between 700 and 800 cm−1at a resolution of 0.004 cm−1. The ν5and 2ν6vibrations of A′ symmetry give rise toa/bhybrid bands with a very predominanta-type component. Due to the proximity of their band origins, thev5 = 1 andv6 = 2 levels perturb each other by Fermi and Coriolis resonances. The interaction mechanisms, previously investigated in the rotational spectra ofClF, were extended to the less abundant isotopic speciesClF and to higherJandKavalues in the main isotopologue. The spectral analysis resulted in the identification of 4188 and 5392 transitions forClF andClF, respectively. All the assigned data were simultaneously fitted using the Watson's A-reduction Hamiltonian in theIrrepresentation and perturbation operators. Excited state parameters, band origins and coupling terms for the ν5/2ν6dyad of both isotopologues were determined. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
18. Jet-cooled diode laser spectrum and FTIR integrated band intensities of CF3Br: rovibrational analysis of 2ν5 and ν2 + ν3 bands near 9 μm and cross-section measurements in the 450-2500 cm-1 region.
- Author
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Pietropolli Charmet, A., Tasinato, N., Stoppa, P., Baldacci, A., and Giorgianni, S.
- Subjects
- *
SPECTRUM analysis , *ABSORPTION , *QUALITATIVE chemical analysis , *RADIATION , *LIGHT beating spectroscopy - Abstract
The high resolution (up to 0.0007 cm-1) infrared diode laser spectrum of CF3Br (Halon 1301) with natural isotopic abundance has been investigated in the region 1090-1130 cm-1, characterized by the presence of the 2ν5 and ν2 + ν3 absorptions and several weaker hot bands. The rovibrational analysis of the data, obtained employing a slit-jet system (rotational temperature of about 50 K) together with those recorded at 200 K, led to a complete and accurate set of spectroscopic constants for the bands of both the bromine isotopologues. Integrated band intensities have been obtained for all the absorptions in the spectral range 450-2500 cm-1. The high resolution data and information concerning the cross-sections of this molecule can be useful for its remote sensing and for better modelling its contribution to global warming. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
19. THE QUANTUM CHEMICAL PREDICTION OF SEXTIC CENTRIFUGAL DISTORTION CONSTANTS: A BENCHMARK STUDY FOR ATMOSPHERIC AND ASTROCHEMICAL APPLICATIONS
- Author
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Boussessi, R., Tasinato, N., Andrea Pietropolli Charmet, Paolo Stoppa, and Barone, V.
- Subjects
Settore CHIM/02 - Chimica Fisica
20. Looking for the Elusive Imine Tautomer of Creatinine: Different States of Aggregation Studied by Quantum Chemistry and Molecular Spectroscopy
- Author
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José L. Alonso, Cristina Puzzarini, Elena R. Alonso, Alice Balbi, Vincenzo Barone, Santiago Mata, Iker León, Lorenzo Spada, Nicola Tasinato, Leon I., Tasinato N., Spada L., Alonso E.R., Mata S., Balbi A., Puzzarini C., Alonso J.L., Barone V., Leon, I., Tasinato, N., Spada, L., Alonso, E. R., Mata, S., Balbi, A., Puzzarini, C., Alonso, J. L., and Barone, V.
- Subjects
Imine ,Infrared spectroscopy ,Quantum chemistry ,quantum chemistry ,chemistry.chemical_compound ,Isomerism ,rotational spectroscopy ,Computational chemistry ,Hyperfine structure ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Spectrum Analysi ,Aqueous solution ,Full Paper ,Spectrum Analysis ,Water ,General Chemistry ,Full Papers ,Tautomer ,vibrational spectroscopy ,tautomerism ,chemistry ,Creatinine ,laser ablation ,Amine gas treating ,Imines ,Rotational spectroscopy - Abstract
New spectroscopic experiments and state‐of‐the‐art quantum‐chemical computations of creatinine in different aggregation states unequivocally unveiled a significant tuning of tautomeric equilibrium by the environment: from the exclusive presence of the amine tautomer in the solid state and aqueous solution to a mixture of amine and imine tautomers in the gas phase. Quantum‐chemical calculations predict the amine species as the most stable tautomer by about 30 kJ mol−1 in condensed phases. On the contrary, moving to the isolated forms, both Z and E imine isomers become more stable by about 7 kJ mol−1. Since the imine isomers and one amine tautomer are separated by significant energy barriers, all of them should be present in the gas phase. This prediction has indeed been confirmed by high‐resolution rotational spectroscopy, which provides the first experimental characterization of the elusive imine tautomer. The interpretation of the complicated hyperfine structure of the rotational spectrum, originated by three 14N nuclei, makes it possible to use the spectral signatures as a sort of fingerprint for each individual tautomer in the complex sample., A journey among the aggregation states of a key biomolecule, creatinine, is reported, guided by state‐of‐the‐art quantum‐chemical computations and spectroscopic techniques. The fine tuning of the creatinine tautomeric equilibrium by different environments is unveiled and fully understood by vis‐à‐vis comparison between simulated and experimental signatures.
- Published
- 2021
21. The Italian National Project of Astrobiology—Life in Space—Origin, Presence, Persistence of Life in Space, from Molecules to Extremophiles
- Author
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Onofri, Silvano, Balucani, Nadia, Barone, Vincenzo, Benedetti, Pietro, Billi, Daniela, Balbi, Amedeo, Brucato, John Robert, Cobucci-Ponzano, Beatrice, Costanzo, Giovanna, La Rocca, Nicoletta, Moracci, Marco, Saladino, Raffaele, Vladilo, Giovanni, Niccolò, Albertini, Mariano, Battistuzzi, Julien, Bloino, Lorenzo, Botta, Piergiorgio, Casavecchia, Alessia, Cassaro, Riccardo, Claudi, Lorenzo, Cocola, Alberto, Coduti, Paola Di Donato, Ernesto Di Mauro, Luca, Dore, Stefano, Falcinelli, Marco, Fulle, Stavro, Ivanovski, Andrea, Lombardi, Giordano, Mancini, Michele, Maris, Luisa, Maurelli, Giuseppe, Murante, Rodolfo, Negri, Claudia, Pacelli, Isabella, Pagano, Davide, Piccinino, Luca, Poletto, Giorgio, Prantera, Cristina, Puzzarini, Sergio, Rampino, Caterina, Ripa, Marzio, Rosi, Monica, Sanna, Laura, Selbmann, Laura, Silva, Dimitrios, Skouteris, Andrea, Strazzulli, Nicola, Tasinato, Anna Maria Timperio, Andrea, Tozzi, Gian Paolo Tozzi, Trainotti, Livio, Piero, Ugliengo, Luigi, Vaccaro, and Laura Zucconi, Onofri, S., Balucani, N., Barone, V., Benedetti, P., Billi, D., Balbi, A., Brucato, J. R., Cobucci-Ponzano, B., Costanzo, G., Rocca, N. L., Moracci, M., Saladino, R., Vladilo, G., Albertini, N., Battistuzzi, M., Bloino, J., Botta, L., Casavecchia, P., Cassaro, A., Claudi, R., Cocola, L., Coduti, A., Di Donato, P., Di Mauro, E., Dore, L., Falcinelli, S., Fulle, M., Ivanovski, S., Lombardi, A., Mancini, G., Maris, M., Maurelli, L., Murante, G., Negri, R., Pacelli, C., Pagano, I., Piccinino, D., Poletto, L., Prantera, G., Puzzarini, C., Rampino, S., Ripa, C., Rosi, M., Sanna, M., Selbmann, L., Silva, L., Skouteris, D., Strazzulli, A., Tasinato, N., Timperio, A. M., Tozzi, A., Tozzi, G. P., Trainotti, L., Ugliengo, P., Vaccaro, L., Zucconi, L., Onofri S., Balucani N., Barone V., Benedetti P., Billi D., Balbi A., Brucato J.R., Cobucci-Ponzano B., Costanzo G., Rocca N.L., Moracci M., Saladino R., Vladilo G., Albertini N., Battistuzzi M., Bloino J., Botta L., Casavecchia P., Cassaro A., Claudi R., Cocola L., Coduti A., Di Donato P., Di Mauro E., Dore L., Falcinelli S., Fulle M., Ivanovski S., Lombardi A., Mancini G., Maris M., Maurelli L., Murante G., Negri R., Pacelli C., Pagano I., Piccinino D., Poletto L., Prantera G., Puzzarini C., Rampino S., Ripa C., Rosi M., Sanna M., Selbmann L., Silva L., Skouteris D., Strazzulli A., Tasinato N., Timperio A.M., Tozzi A., Tozzi G.P., Trainotti L., Ugliengo P., Vaccaro L., and Zucconi L.
- Subjects
Persistence (psychology) ,Extremophiles ,Exobiology ,Extraterrestrial Environment ,Origin of Life ,Origin of Life in Space ,Space (commercial competition) ,Astrobiology, Life in Space, From Molecules to Extremophiles ,Astrobiology ,Abiogenesis ,From Molecules to Extremophiles ,Extremophile ,Life in Space ,Origin of life, space, exobiology ,News and Views ,extremophiles ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Settore FIS/05 ,Chemistry ,space ,Agricultural and Biological Sciences (miscellaneous) ,Space and Planetary Science ,astrobiology ,from Molecules to Extremophiles in space - Abstract
THE ''LIfe in Space'' project was funded in the wake of the Italian Space Agency's proposal for the development of a network of institutions and laboratories conceived to implement Italian participation in space astrobiology experiments. Of primary concern for this project is the study of the origin of life in the Universe, a focus that will promote investigation into prebiotic chemistry in various possible scenarios, whether in polar or nonpolar solvents (e.g., Titan's environment). Such results will link with study of the effects of simulated space conditions on possible chemical bio- signatures. The limits of life as we know it will be investigated in ground-based experiments with microorganisms that have already demonstrated their resistance to extreme environments on Earth and to real or simulated space conditions. The potential survival of microorganisms will also be examined with up-to-date molecular methods. The ability of some microorganisms to produce atmospheric and surface biosignatures when exposed to simulated conditions will be tested and compared with the possible existence of bio- signatures on potentially habitable exoplanets. Furthermore, the search for potentially habitable exoplanets, with space- based observational methods, will be optimized by way of dedicated climate models with the capacity to predict the detectability of atmospheric biosignatures for a broad range of planetary conditions. The project embraces the four most important topics in astrobiological research, as listed below, along with relevant contributions from the participating Italian institutions. Origins and evolution of organic compounds of biological significance in space (comets, asteroids, rocky planets, and moons); Prebiotic syntheses, origin of life, and early life; The limits of life and biological habitability: origin, evolution and adaptation of life in extreme environments on Earth and in space; Biomarkers for life detection in the Solar System and on exoplanets.
- Published
- 2020
22. The Role of State-of-the-Art Quantum-Chemical Calculations in Astrochemistry: Formation Route and Spectroscopy of Ethanimine as a Paradigmatic Case
- Author
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Cristina Puzzarini, Vincenzo Barone, Carmen Baiano, Nicola Tasinato, Jacopo Lupi, Baiano, C., Lupi, J., Tasinato, N., Puzzarini, C., Barone, V., Baiano C., Lupi J., Tasinato N., Puzzarini C., and Barone V.
- Subjects
prebiotic chemistry ,Extraterrestrial Environment ,Pharmaceutical Science ,01 natural sciences ,Analytical Chemistry ,quantum chemistry ,chemistry.chemical_compound ,Computational chemistry ,Drug Discovery ,010303 astronomy & astrophysics ,Spectroscopy ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Physics ,010304 chemical physics ,Molecular Structure ,Methyl radical ,Computational Physics (physics.comp-ph) ,Ethanimine ,Chemistry (miscellaneous) ,Molecular Medicine ,Quantum chemistry ,Physics - Computational Physics ,spectroscopy ,Astrochemistry ,FOS: Physical sciences ,Article ,lcsh:QD241-441 ,lcsh:Organic chemistry ,Isomerism ,Physics - Chemical Physics ,0103 physical sciences ,Molecule ,Physical and Theoretical Chemistry ,Prebiotic chemistry ,Chemical Physics (physics.chem-ph) ,Kinetic ,ethanimine ,Amidogen ,Spectrum Analysis ,Organic Chemistry ,Astrophysics - Astrophysics of Galaxies ,Interstellar medium ,chemistry ,kinetics ,Astrophysics of Galaxies (astro-ph.GA) ,Quantum Theory ,Hydrogen - Abstract
The gas-phase formation and spectroscopic characteristics of ethanimine have been re-investigated as a paradigmatic case illustrating the accuracy of state-of-the-art quantum-chemical (QC) methodologies in the field of astrochemistry. According to our computations, the reaction between the amidogen, NH, and ethyl, C$_2$H$_5$, radicals is very fast, close to the gas-kinetics limit. Although the main reaction channel under conditions typical of the interstellar medium leads to methanimine and the methyl radical, the predicted amount of the two E,Z stereoisomers of ethanimine is around 10%. State-of-the-art QC and kinetic models lead to a [E-CH$_3$CHNH]/[Z-CH$_3$CHNH] ratio of ca. 1.4, slightly higher than the previous computations, but still far from the value determined from astronomical observations (ca. 3). An accurate computational characterization of the molecular structure, energetics, and spectroscopic properties of the E and Z isomers of ethanimine combined with millimeter-wave measurements up to 300 GHz, allows for predicting the rotational spectrum of both isomers up to 500 GHz, thus opening the way toward new astronomical observations., 21 pages, 5 figures
- Published
- 2020
23. A twist on the reaction of the CN radical with methylamine in the interstellar medium: new hints from a state-of-the-art quantum-chemical study
- Author
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Cristina Puzzarini, Zoi Salta, Vincenzo Barone, Nicola Tasinato, Jacopo Lupi, Carlo Cavallotti, Puzzarini, C., Salta, Z., Tasinato, N., Lupi, J., Cavallotti, C., Barone, V., Puzzarini C., Salta Z., Tasinato N., Lupi J., Cavallotti C., and Barone V.
- Subjects
Astrochemistry ,Radical ,FOS: Physical sciences ,ISM: molecule ,01 natural sciences ,Molecular processes ,Organic molecules ,Gas phase ,chemistry.chemical_compound ,Computational chemistry ,Physics - Chemical Physics ,0103 physical sciences ,molecule [ISM] ,Twist ,010303 astronomy & astrophysics ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Quantum chemical ,Physics ,Chemical Physics (physics.chem-ph) ,010304 chemical physics ,Methylamine ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Interstellar medium ,chemistry ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) - Abstract
Despite the fact that the majority of current models assume that interstellar complex organic molecules (iCOMs) are formed on dust-grain surfaces, there is some evidence that neutral gas-phase reactions play an important role. In this paper, we investigate the reaction occurring in the gas phase between methylamine (CH$_3$NH$_2$) and the cyano (CN) radical, for which only fragmentary and/or inaccurate results have been reported to date. This case study allows us to point out the pivotal importance of employing quantum-chemical calculations at the state of the art. Since the two major products of the CH$_3$NH$_2$ + CN reaction, namely the CH$_3$NH and CH$_2$NH$_2$ radicals, have not been spectroscopically characterized yet, some effort has been made for filling this gap., 14 pages, 6 figures, MNRAS in press
- Published
- 2020
24. Accuracy and Interpretability: The Devil and the Holy Grail. New Routes across Old Boundaries in Computational Spectroscopy
- Author
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Vincenzo Barone, Julien Bloino, Nicola Tasinato, Cristina Puzzarini, Puzzarini, C., Bloino, J., Tasinato, N., Barone, V., Puzzarini C., Bloino J., Tasinato N., and Barone V.
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spectroscopic accuracy ,Dichotomy ,010405 organic chemistry ,Chemistry ,business.industry ,Interpretation (philosophy) ,General Chemistry ,Molecular spectroscopy ,010402 general chemistry ,01 natural sciences ,Data science ,vibrational spectroscopy ,Field (computer science) ,0104 chemical sciences ,Holy Grail ,Software ,rotational spectroscopy ,computational methodology ,Spectroscopy ,business ,computational spectroscopy ,Interpretability - Abstract
The past decade has witnessed an increasing interaction between experiment and theory in the field of molecular spectroscopy. On the computational side, ongoing developments of hardware and software have moved computational spectroscopy from a highly specialized research area to a general tool for researchers in different fields of chemical science. However, since its dawn, computational spectroscopy has been characterized by the dichotomies of qualitative and quantitative description, and of interpretation and accuracy. Indeed, the analysis of experiments is seldom straightforward because of the subtle interplay of several different effects, which are not easy to evaluate and isolate, and/or the complexity of the system under consideration. Often, the accuracy has to be set aside for a more qualitative analysis that will provide the means for a broad interpretation. In such a scenario, the most recent advances in theoretical treatments as well as computational tools have opened the way to the reconciliation of accuracy and interpretability, resulting in unequivocal analyses and assignments of experimental spectra and their unbiased interpretation. This Review aims at being a comprehensive, authoritative, critical, and readable account of general interest to the chemistry community because of the wealth of qualitative and quantitative information that can be obtained from spectroscopic investigations. Limiting ourselves to rotational and vibrational spectroscopy, emphasis will be put on accuracy and interpretability as well as on the routes toward their reconciliation and integration.
- Published
- 2019
25. Accurate Biomolecular Structures by the Nano-LEGO Approach: Pick the Bricks and Build Your Geometry
- Author
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Giorgia Ceselin, Vincenzo Barone, Nicola Tasinato, Ceselin, G., Barone, V., and Tasinato, N.
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Physics ,Molecular Structure ,Spectrum Analysis ,Quantum chemical computations ,Small deviations ,Ranging ,Electronic structure ,Article ,Computer Science Applications ,Nano ,Quantum Theory ,Molecule ,Density functional theory ,Statistical physics ,Physical and Theoretical Chemistry ,Spectroscopy ,Spectrum Analysi ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali - Abstract
The determination of accurate equilibrium molecular structures plays a fundamental role for understanding many physical-chemical properties of molecules, ranging from the precise evaluation of the electronic structure to the analysis of the role played by dynamical and environmental effects in tuning their overall behavior. For small semi-rigid systems in the gas phase, state-of-the-art quantum chemical computations rival the most sophisticated experimental (from, for example, high-resolution spectroscopy) results. For larger molecules, more effective computational approaches must be devised. To this end, we have further enlarged the compilation of available semi-experimental (SE) equilibrium structures, now covering the most important fragments containing H, B, C, N, O, F, P, S, and Cl atoms collected in the new SE100 database. Next, comparison with geometries optimized by methods rooted in the density functional theory showed that the already remarkable results delivered by PW6B95 and, especially, rev-DSDPBEP86 functionals can be further improved by a linear regression (LR) approach. Use of template fragments (taken from the SE100 library) together with LR estimates for the missing interfragment parameters paves the route toward accurate structures of large molecules, as witnessed by the very small deviations between computed and experimental rotational constants. The whole approach has been implemented in a user-friendly tool, termed nano-LEGO, and applied to a number of demanding case studies.
- Published
- 2021
26. Development and Validation of a Parameter-Free Model Chemistry for the Computation of Reliable Reaction Rates
- Author
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Vincenzo Barone, Nicola Tasinato, Zoi Salta, Jacopo Lupi, Barone, V., Lupi, J., Salta, Z., and Tasinato, N.
- Subjects
Chemical Physics (physics.chem-ph) ,Computation ,Ab initio ,FOS: Physical sciences ,Zero-point energy ,Computational Physics (physics.comp-ph) ,Article ,Computer Science Applications ,Reaction rate ,Test case ,Physics - Chemical Physics ,Master equation ,Range (statistics) ,Statistical physics ,Physical and Theoretical Chemistry ,Physics - Computational Physics ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Energy (signal processing) - Abstract
A recently developed model chemistry (jun-Cheap) has been slightly modified and proposed as an effective, reliable and parameter-free scheme for the computation of accurate reaction rates with special reference to astrochemical and atmospheric processes. Benchmarks with different sets of state-of-the-art energy barriers spanning a wide range of values show that, in the absence of strong multi-reference contributions, the proposed model outperforms the most well-known model chemistries, reaching a sub-chemical accuracy without any empirical parameter and with affordable computer times. Some test cases show that geometries, energy barriers, zero point energies and thermal contributions computed at this level can be used in the framework of the master equation approach based on ab-initio transition state theory (AITSTME) for obtaining accurate reaction rates., JCTC
- Published
- 2021
27. Gliding on Ice in search of accurate and cost-effective computational methods for Astrochemistry on Grains: the puzzling case of the HCN isomerization
- Author
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Carmen Baiano, Jacopo Lupi, Vincenzo Barone, Nicola Tasinato, Baiano, C., Lupi, J., Barone, V., and Tasinato, N.
- Subjects
Chemical Physics (physics.chem-ph) ,Isomerization ,Cluster chemistry ,Mathematical method ,FOS: Physical sciences ,Computational Physics (physics.comp-ph) ,Molecules ,Astrophysics - Astrophysics of Galaxies ,Computer Science Applications ,Astrophysics of Galaxies (astro-ph.GA) ,Physics - Chemical Physics ,Physical and Theoretical Chemistry ,Physics - Computational Physics ,Basis set ,Settore CHIM/02 - Chimica Fisica - Abstract
The isomerization of hydrogen cyanide to hydrogen isocyanide on icy grain surfaces is investigated by an accurate composite method (jun-Cheap) rooted in the coupled cluster ansatz and by density functional approaches. After benchmarking density functional predictions of both geometries and reaction energies against jun-Cheap results for the relatively small model system HCN -- (H2O)2 the best performing DFT methods are selected. A large cluster containing 20 water molecules is then employed within a QM/QM$'$ approach to include a realistic environment mimicking the surface of icy grains. Our results indicate that four water molecules are directly involved in a proton relay mechanism, which strongly reduces the activation energy with respect to the direct hydrogen transfer occurring in the isolated molecule. Further extension of the size of the cluster up to 192 water molecules in the framework of a three-layer QM/QM'/MM model has a negligible effect on the energy barrier ruling the isomerization. Computation of reaction rates by transition state theory indicates that on icy surfaces the isomerization of HNC to HCN could occur quite easily even at low temperatures thanks to the reduced activation energy that can be effectively overcome by tunneling., Accepted on JCTC
- Published
- 2022
28. The Spectroscopic Characterization of Halogenated Pollutants through the Interplay between Theory and Experiment: Application to R1122
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Andrea Pietropolli Charmet, Giorgia Ceselin, Paolo Stoppa, Nicola Tasinato, Charmet, A. P., Ceselin, G., Stoppa, P., and Tasinato, N.
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Ro-vibrational spectroscopy ,ro-vibrational spectroscopy ,Organic Chemistry ,Pharmaceutical Science ,Analytical Chemistry ,Environmental chemistry ,IR spectroscopy ,Quantum chemical calculations ,QD241-441 ,Chemistry (miscellaneous) ,Drug Discovery ,Molecular Medicine ,quantum chemical calculations ,Quantum chemical calculation ,environmental chemistry ,Physical and Theoretical Chemistry ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Settore CHIM/02 - Chimica Fisica - Abstract
In the last decade, halogenated ethenes have seen an increasing interest for different applications; in particular, in refrigeration, air-conditioning and heat pumping. At the same time, their adverse effects as atmospheric pollutants require environmental monitoring, especially by remote sensing spectroscopic techniques. For this purpose, an accurate characterization of the spectroscopic fingerprint—in particular, those of relevance for rotational–vibrational spectroscopy—of the target molecules is strongly needed. This work provides an integrated computational–theoretical investigation on R1122 (2-Chloro-1,1-difluoro-ethylene, ClHC=CF2), a compound widely employed as a key intermediate in different chemical processes. State-of-the-art quantum chemical calculations relying on CCSD(T)-based composite schemes and hybrid CCSD(T)/DFT approaches are used to obtain an accurate prediction of the structural, rotational and vibrational spectroscopic properties. In addition, the equilibrium geometry is obtained by exploiting the semi-experimental method. The theoretical predictions are used to guide the analysis of the experimentally recorded gas-phase infrared spectrum, which is assigned in the 400–6500 cm−1 region. Furthermore, absorption cross sections are accurately determined over the same spectral range. Finally, by using the obtained spectroscopic data, a first estimate of the global warming potential of R1122 vibrational spectra is obtained.
- Published
- 2021
29. Isomerization and Fragmentation Reactions on the [C2SH4] Potential Energy Surface: The Metastable Thione S-Methylide Isomer
- Author
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Nicola Tasinato, Zoi Salta, Oscar N. Ventura, Vincenzo Barone, Aline Katz, Marc E. Segovia, Salta, Z., Segovia, M. E., Katz, A., Tasinato, N., Barone, V., and Ventura, O. N.
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,chemistry.chemical_compound ,Thiirane ,chemistry ,Fragmentation (mass spectrometry) ,Ylide ,Metastability ,Potential energy surface ,Thiol ,Isomerization ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali - Abstract
Thione S-methylide, parent species of the thiocarbonyl ylide family, is a 1,3-dipolar species on the [C2SH4] potential energy surface, not so much studied as its isomers, thiirane, vinyl thiol, and thioacetaldehyde. The conrotatory ring-closure reaction toward thiirane was studied in the 90s, but no complete analysis of the potential energy surface is available. In this paper, we report a computational study of the reaction scheme linking all species. We employed several computational methods (density functional theory, CCSD(T) composite schemes, and CASSCF/CASPT2 multireference procedures) to find the best description of thione S-methylide, its isomers, and transition states. The barrier from thiirane to thione S-methylide amounts to 52.2 kcal mol-1 (against 17.6 kcal mol-1 for the direct one), explaining why thiocarbonyl ylides cannot be prepared from thiiranes. Conversion of thiirane to vinyl thiol implies a large barrier, supporting why the reaction has been observed only at high temperatures. Fragmentations of thiirane to S(3P) or S(1D) and ethylene as well as decomposition to hydrogen sulfide plus acetylene were also explored. Triplet and singlet open-shell species were identified as intermediates in the fragmentations, with energies lower than the transition state between thiirane and vinyl thiol, explaining the preference of the latter at low temperatures. Thione S-methylide, parent species of the thiocarbonyl ylide family, is a 1,3-dipolar species on the [C2SH4] potential energy surface, not so much studied as its isomers, thiirane, vinyl thiol, and thioacetaldehyde. The conrotatory ring-closure reaction toward thiirane was studied in the 90s, but no complete analysis of the potential energy surface is available. In this paper, we report a computational study of the reaction scheme linking all species. We employed several computational methods (density functional theory, CCSD(T) composite schemes, and CASSCF/CASPT2 multireference procedures) to find the best description of thione S-methylide, its isomers, and transition states. The barrier from thiirane to thione S-methylide amounts to 52.2 kcal mol-1 (against 17.6 kcal mol-1 for the direct one), explaining why thiocarbonyl ylides cannot be prepared from thiiranes. Conversion of thiirane to vinyl thiol implies a large barrier, supporting why the reaction has been observed only at high temperatures. Fragmentations of thiirane to S(3P) or S(1D) and ethylene as well as decomposition to hydrogen sulfide plus acetylene were also explored. Triplet and singlet open-shell species were identified as intermediates in the fragmentations, with energies lower than the transition state between thiirane and vinyl thiol, explaining the preference of the latter at low temperatures.
- Published
- 2021
30. A computational insight into the relationship between side chain IR line shapes and local environment in fibril-like structures
- Author
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Laura Zanetti-Polzi, Vincenzo Barone, Sandra Mónica Vieira Pinto, Nicola Tasinato, Isabella Daidone, Pinto, S. M. V., Tasinato, N., Barone, V., Zanetti-Polzi, L., and Daidone, I.
- Subjects
Materials science ,Spectrophotometry, Infrared ,Infrared Rays ,Infrared ,Glutamine ,General Physics and Astronomy ,Infrared spectroscopy ,Molecular Dynamics Simulation ,010402 general chemistry ,01 natural sciences ,Turn (biochemistry) ,Protein structure ,0103 physical sciences ,Side chain ,Physical and Theoretical Chemistry ,Protein secondary structure ,Settore CHIM/02 - Chimica Fisica ,Quantitative Biology::Biomolecules ,010304 chemical physics ,Hydrogen bond ,Quantitative Biology::Molecular Networks ,Water ,Hydrogen Bonding ,Amides ,0104 chemical sciences ,Chemical physics ,Isotope Labeling ,Peptides - Abstract
Infrared spectroscopy is a widely used technique to characterize protein structures and protein mediated processes. While the amide I band provides information on proteins' secondary structure, amino acid side chains are used as infrared probes for the investigation of protein reactions and local properties. In this paper, we use a hybrid quantum mechanical/classical molecular dynamical approach based on the perturbed matrix method to compute the infrared band due to the C=O stretching mode of amide-containing side chains. We calculate, at first, the infrared band of zwitterionic glutamine in water and obtain results in very good agreement with the experimental data. Then, we compute the signal arising from glutamine side chains in a microcrystal of the yeast prion Sup35-derived peptide, GNNQQNY, with a fibrillar structure. The infrared bands obtained by selective isotopic labeling of the two glutamine residues, Q4 and Q5, of each peptide were experimentally used to investigate the local hydration in the fibrillar microcrystal. The experimental spectra of the two glutamine residues, which experience different hydration environments, feature different spectral signals that are well reproduced by the corresponding calculated spectra. In addition, the analysis of the simulated spectra clarifies the molecular origin of the experimentally observed spectroscopic differences that arise from the different local electric field experienced by the two glutamine residues, which is, in turn, determined by a different hydrogen bonding pattern.
- Published
- 2021
31. A computational journey across nitroxide radicals: From structure to spectroscopic properties and beyond
- Author
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Vincenzo Barone, Marco Fusè, Sandra Mónica Vieira Pinto, Nicola Tasinato, Barone, V., Fuse', M., Pinto, S. M. V., and Tasinato, N.
- Subjects
Large amplitude motion ,Organic Chemistry ,Anharmonicity ,Pharmaceutical Science ,Geometry ,IR spectra ,Magnetic properties ,Nitroxide radicals ,Article ,Analytical Chemistry ,QD241-441 ,Chemistry (miscellaneous) ,Drug Discovery ,Magnetic propertie ,Molecular Medicine ,nitroxide radicals ,geometry ,magnetic properties ,anharmonicity ,large amplitude motion ,Physical and Theoretical Chemistry ,Settore CHIM/02 - Chimica Fisica - Abstract
Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest. Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest.
- Published
- 2021
32. Accuracy meets interpretability for computational spectroscopy by means of hybrid and double-hybrid functionals
- Author
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Vincenzo Barone, Nicola Tasinato, Giorgia Ceselin, Marco Fusè, Barone, V., Ceselin, G., Fuse', M., and Tasinato, N.
- Subjects
Vibrational spectroscopy ,Rotational spectroscopy ,Computer science ,02 engineering and technology ,010402 general chemistry ,Benchmark ,01 natural sciences ,lcsh:Chemistry ,Astrochemical molecule ,Rigid rotor ,Astrochemical molecules ,Atmospheric molecules ,Density functional theory ,Quantum chemistry ,Harmonic oscillator ,Original Research ,Interpretability ,Settore CHIM/02 - Chimica Fisica ,Basis (linear algebra) ,Atmospheric molecule ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Hybrid functional ,Chemistry ,lcsh:QD1-999 ,Perturbation theory (quantum mechanics) ,0210 nano-technology ,Algorithm - Abstract
Accuracy and interpretability are often seen as the devil and holy grail in computational spectroscopy and their reconciliation remains a primary research goal. In the last few decades, density functional theory has revolutionized the situation, paving the way to reliable yet effective models for medium size molecules, which could also be profitably used by non-specialists. In this contribution we will compare the results of some widely used hybrid and double hybrid functionals with the aim of defining the most suitable recipe for all the spectroscopic parameters of interest in rotational and vibrational spectroscopy, going beyond the rigid rotor/harmonic oscillator model. We will show that last-generation hybrid and double hybrid functionals in conjunction with partially augmented double-and triple-zeta basis sets can offer, in the framework of second order vibrational perturbation theory, a general, robust, and user-friendly tool with unprecedented accuracy for medium-size semi-rigid molecules. Accuracy and interpretability are often seen as the devil and holy grail in computational spectroscopy and their reconciliation remains a primary research goal. In the last few decades, density functional theory has revolutionized the situation, paving the way to reliable yet effective models for medium size molecules, which could also be profitably used by non-specialists. In this contribution we will compare the results of some widely used hybrid and double hybrid functionals with the aim of defining the most suitable recipe for all the spectroscopic parameters of interest in rotational and vibrational spectroscopy, going beyond the rigid rotor/harmonic oscillator model. We will show that last-generation hybrid and double hybrid functionals in conjunction with partially augmented double-and triple-zeta basis sets can offer, in the framework of second order vibrational perturbation theory, a general, robust, and user-friendly tool with unprecedented accuracy for medium-size semi-rigid molecules.
- Published
- 2020
33. Reinvestigation of the Deceptively Simple Reaction of Toluene with OH and the Fate of the Benzyl Radical: The 'hidden' Routes to Cresols and Benzaldehyde
- Author
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Martina Kieninger, Agnie M. Kosmas, Nicola Tasinato, Marc E. Segovia, Vincenzo Barone, Oscar N. Ventura, Zoi Salta, Salta, Z., Kosmas, A. M., Segovia, M. E., Kieninger, M., Tasinato, N., Barone, V., and Ventura, O. N.
- Subjects
Quantum chemical ,010304 chemical physics ,macromolecular substances ,Cresol ,010402 general chemistry ,01 natural sciences ,Toluene ,Medicinal chemistry ,Article ,0104 chemical sciences ,Benzaldehyde ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,medicine ,Hydroxyl radical ,Physical and Theoretical Chemistry ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali ,Methyl group ,medicine.drug ,Settore CHIM/02 - Chimica Fisica - Abstract
In a previous work, we have investigated the initial steps of the reaction of toluene with the hydroxyl radical using several quantum chemical approaches including density functional and composite post-Hartree–Fock models. Comparison of H-abstraction from the methyl group and additions at different positions of the phenyl ring showed that the former reaction channel is favored at room temperature. This conclusion appears at first sight incompatible with the experimental observation of a lower abundance of the product obtained from abstraction (benzaldehyde) with respect to those originating from addition (cresols). Further reactions of the intermediate radicals with oxygen, water, and additional OH radicals are explored in this paper through theoretical calculations on more than 120 species on the corresponding potential energy surface. The study of the addition reactions, to obtain the cresols through hydroxy methylcyclodienyl intermediate radicals, showed that only in the case of o-cresol the reaction proceeds by addition of O2 to the ring, internal H-transfer, and hydroperoxyl abstraction and not through direct H-abstraction. For both p- and m-cresol, instead, the reaction occurs through a higher-energy direct H-abstraction, thus explaining in part the observed larger concentration of the ortho isomer in the final products. It was also found that the benzyl radical, formed by H-abstraction from the methyl group, is able to react further if additional OH is present. Two reaction paths leading to o-cresol, two leading to p-cresol, and one leading to m-cresol were determined. Moreover, in this situation, the benzyl radical is predicted to produce benzyl alcohol, as was found in some experiments. The commonly accepted route to benzaldehyde was found to be not the energetically favored one. Instead, a route leading to the benzoyl radical (and ultimately to benzoic acid) with the participation of one water molecule was clearly more favorable, both thermodynamically and kinetically.
- Published
- 2020
34. Towards the SMART workflow system for computational spectroscopy
- Author
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Marco Mendolicchio, Vincenzo Barone, Marco Fusè, Giordano Mancini, Nicola Tasinato, Daniele Licari, Andrea Salvadori, Licari, D., Fusè, M., Salvadori, A., Tasinato, N., Mendolicchio, M., Mancini, G., and Barone, V.
- Subjects
010304 chemical physics ,Computer science ,Process (engineering) ,General Physics and Astronomy ,010402 general chemistry ,01 natural sciences ,Data science ,Data type ,Field (computer science) ,0104 chemical sciences ,Visualization ,Workflow ,Cyberinfrastructure ,0103 physical sciences ,Unsupervised learning ,Applied research ,Physical and Theoretical Chemistry ,Settore CHIM/12 - Chimica dell'Ambiente e dei Beni Culturali - Abstract
Is it possible to convert highly specialized research in the field of computational spectroscopy into robust and user-friendly aids to experiments and industrial applications? What kind of tools should be created to increase the interactions between researchers with different backgrounds and push towards new frontiers in computational chemistry? The outstanding advances in computational spectroscopy and the wide availability of computational and analytical tools are paving the route toward the study of problems that were previously difficult or impossible to solve and enable the imagination of even more ambitious targets for fundamental and applied research. The combination of new computer- and data-centric technologies is transforming data analysis from an uncommon and retrospective practice into a proactive process of strategic decision and action. This paper starts from these premises and proposes a perspective for a new cyberinfrastructure aimed at integrating developments in theory, algorithms and software with new tools for workflow management, data mining and visualization. We make a case for this approach by means of a few examples that deal with unmanageable types of data in molecular modelling and results obtained using different unsupervised learning algorithms. Is it possible to convert highly specialized research in the field of computational spectroscopy into robust and user-friendly aids to experiments and industrial applications? What kind of tools should be created to increase the interactions between researchers with different backgrounds and push towards new frontiers in computational chemistry? The outstanding advances in computational spectroscopy and the wide availability of computational and analytical tools are paving the route toward the study of problems that were previously difficult or impossible to solve and enable the imagination of even more ambitious targets for fundamental and applied research. The combination of new computer- and data-centric technologies is transforming data analysis from an uncommon and retrospective practice into a proactive process of strategic decision and action. This paper starts from these premises and proposes a perspective for a new cyberinfrastructure aimed at integrating developments in theory, algorithms and software with new tools for workflow management, data mining and visualization. We make a case for this approach by means of a few examples that deal with unmanageable types of data in molecular modelling and results obtained using different unsupervised learning algorithms.
- Published
- 2018
35. Virtual Reality bridge between Chemistry and Cultural Heritage: the 'Sala degli Stemmi' Case Study
- Author
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N Tasinato, M Martino, V Barone, F Lazzari, Martino, M, Lazzari, F, Tasinato, N, and Barone, V
- Subjects
Cultural heritage ,Architectural engineering ,Engineering ,business.industry ,Chemistry (relationship) ,Virtual reality ,business ,Bridge (interpersonal) ,Settore CHIM/02 - Chimica Fisica - Abstract
In this contribution, we present a multiscale and multidisciplinary VR architecture that aims at creating a common environment where cultural heritage and chemistry meet in order to strengthen the role already played by chemistry in the process of restoration of cultural goods. Our aim is to create a user friendly platform where experts of both fields can share data and ideas in a direct way, in order to achieve deeper insights into cultural goods combining the scientific and historical points of view. As a case study we present the 3D reconstruction of the “Sala degli Stemmi”, which is one of the two historical rooms at Palazzo della Carovana in Pisa, presenting a number of artworks that underwent a process of chemical analysis and restoration in 2012. The whole architecture has been developed using the Unity game engine, and it is usable with HTC Vive headsets. The implementation of the VR environment and the potential applications, from both the scientific and educational points of view, are discussed in some detail.
- Published
- 2020
36. DFT meets the segmented polarization consistent basis sets: Performances in the computation of molecular structures, rotational and vibrational spectroscopic properties
- Author
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Rahma Boussessi, Giorgia Ceselin, Vincenzo Barone, Nicola Tasinato, Boussessi, R., Ceselin, G., Tasinato, N., and Barone, V.
- Subjects
Quantum-chemical calculation ,Rotational spectroscopy ,010405 organic chemistry ,Chemistry ,Computation ,Organic Chemistry ,Equilibrium geometry ,Benchmark ,010402 general chemistry ,Polarization (waves) ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Analytical Chemistry ,Computational physics ,Inorganic Chemistry ,Bond length ,Coupled cluster ,Quartic function ,Infrared spectroscopy ,Spectroscopy ,Basis set - Abstract
Quantum-chemical calculations assist the analysis of laboratory spectra, and often provide the only means to determine spectroscopic data that cannot be accessed experimentally. For the purpose, reliable predictions of structural and spectroscopic parameters are required. Although coupled cluster theory in conjunction with to large basis sets and composite schemes can reach impressive accuracies for structural, thermochemical and spectroscopic properties, it is still limited to small sized molecules. DFT represents the working option for medium to large molecular systems. In this context, systematic investigations are required aimed at characterizing the performances of the different DFT model chemistries. In this work, the accuracy of the popular hybrid B3LYP and the double hybrid B2PLYP functionals coupled to the segmented polarization consistent (aug-)pcs-n basis sets in the prediction of molecular structures and rotational- and vibrational spectroscopic parameters are investigated using a benchmark set of molecules of both atmospheric and astrochemical relevance. For comparison purposes, different flavors of Dunning’s triple-ζ basis sets and the SNSD basis set, are also employed. The convergence behavior of the pcs-n hierarchy with n = 1–4 is also addressed to some extent. The results indicate the B3LYP-D3 functional in conjunction with the aug-pcs-1 or SNSD basis sets as a cost-effective model chemistry for applications in the field of rotational and vibrational spectroscopies. Improved accuracy is obtained by coupling the B2PLYP-D3 functional with the aug-pcs-2 or aug-cc-pVTZ triple-ζ basis sets that show an accuracy around 0.003 A and 0.3° for bond lengths and angles, 1% and 3% for rotational and quartic centrifugal distortion constants, respectively, 12 cm−1 for fundamental frequencies and 3 km mol−1 for IR intensities. The B2PLYP-D3/maug-cc-pVTZ-dH level keeps the same accuracy, with slightly larger deviations for intensities.
- Published
- 2020
37. FTIR spectrum of vinyl fluoride near 3.6 μm: rovibrational analysis of the ν4+ν7band and modelling Coriolis resonances in a seven-level polyad
- Author
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Paolo Stoppa, A. Pietropolli Charmet, Nicola Tasinato, Santi Giorgianni, Alberto Gambi, A. De Lorenzi, Stoppa, P., De Lorenzi, A., Pietropolli Charmet, A., Giorgianni, S., Tasinato, N., and Gambi, A.
- Subjects
Materials science ,Infrared ,ro-vibrational analysis ,Analytical chemistry ,Biophysics ,spectroscopic parameter ,Condensed Matter Physic ,010402 general chemistry ,01 natural sciences ,Coriolis interactions ,infrared spectrum ,spectroscopic parameters ,Vinyl fluoride ,Molecular Biology ,Condensed Matter Physics ,Physical and Theoretical Chemistry ,ro-vibrational analysi ,chemistry.chemical_compound ,symbols.namesake ,0103 physical sciences ,Fourier transform infrared spectroscopy ,Settore CHIM/02 - Chimica Fisica ,010304 chemical physics ,Rotational–vibrational spectroscopy ,Polyad ,0104 chemical sciences ,Fourier transform ,chemistry ,Biophysic ,symbols ,Coriolis interaction - Abstract
The Fourier transform infrared (FTIR) spectrum of vinyl fluoride, H2C=CHF, has been widely investigated in the region of the ν4+ν7 combination band around 2800 cm−1 at a resolution of 0.005 cm−1. This vibration of A' symmetry gives rise to an a/b-hybrid band with a predominant a-type component. The rovibrational structure is strongly perturbed and the analysis has been rather complicated since this combination band is involved at least in a seven-level interacting polyad, including the ν8+2ν10, 2ν8+ν10, 2ν7+ν9, ν7+ν8+ν12, ν5+ν9+ν10 and ν7+ν10+ν12 vibrational states. The study has been further complicated by the absence of transitions coming from the perturbers that were considered as dark states. The spectral analysis resulted in the identification of 936 transitions with J" ≤ 46 and Ka" ≤ 11, all belonging to the a-type component. Most of the assigned data have been fitted using the Watson's A-reduction Hamiltonian in the Ir representation and proper Coriolis perturbation operators. The model employed includes seven different resonances within a complex polyad resonant system and a set of spectroscopic constants for the ν4+ν7 combination band, for the dark states, and Coriolis coupling coefficients have been determined.
- Published
- 2018
38. High-resolution FTIR spectroscopy of HCFC-31 in the 950−1160 cm−1region: rovibrational analysis and resonances in the ν4, ν9and ν5+ν6bands of CH235ClF
- Author
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Agostino Baldacci, Elisabetta Cané, Santi Giorgianni, A. Pietropolli Charmet, Filippo Tamassia, Nicola Tasinato, Mattia Villa, Paolo Stoppa, Stoppa, P., Baldacci, A., Tasinato, Nicola, Charmet, A. Pietropolli, Giorgianni, S., Tamassia, F., Cané, E., Villa, M., Tasinato, N., Charmet, A.P., and Cane, E.
- Subjects
Chemistry ,Infrared ,chlorofluoromethane ,Resolution (electron density) ,Biophysics ,Analytical chemistry ,infrared spectrum ,spectroscopic parameters ,Coriolis interaction ,rovibrational mixing ,Rotational–vibrational spectroscopy ,Condensed Matter Physics ,Molecular physics ,Symmetry (physics) ,Spectral line ,Vibration ,chemistry.chemical_compound ,Chlorofluoromethane ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Molecular Biology ,Infrared spectrum ,Settore CHIM/02 - Chimica Fisica - Abstract
The FTIR spectrum of CH2ClF (natural isotopic mixture) was investigated in the ν4, ν9 and ν5 + ν6 band region between 950 and 1160 cm-1 at the resolution of 0.004 cm-1. The ν4 and ν5 + ν6 vibrations of A′ symmetry give rise to a/b hybrid bands with a predominant a-type component. The ν9 vibration of A″ symmetry, expected with a c-type band contour, shows an intense Coriolis-induced parallel component (ΔKa = 0, ΔKc = 0) derived from mixing with the ν4 = 1 vibrational state. The high-resolution spectra of ν9 and ν5 + ν6 have been analyzed for the first time, while the assignments of the ν4 band, previously investigated, have been extended to higher J and Ka values in the b-type component. The spectral analysis resulted in the identification of 1508, 809 and 349 transitions for the ν4, ν9 and ν5 + ν6 bands of CH2 35ClF, respectively. Besides the strong first-order a- and b-type Coriolis resonances between ν4 and ν9, the ν5 + ν6 vibration was found to interact through a c-type Coriolis with the ν4 and 3ν6. High-order anharmonic resonance (ΔKa = ±2) between ν4 and ν5 + ν6 was also established. All the assigned data were simultaneously fitted using the Watson's A-reduction Hamiltonian in the Ir representation and the relevant perturbation operators. The model employed includes five types of resonances within the tetrad ν4/ν9/ν5 + ν6/3ν6. A set of spectroscopic constants for ν4, ν9 and ν5 + ν6 bands as well as parameters for the dark state 3ν6 and seven coupling terms have been determined. The simulations performed in different spectral regions satisfactorily reproduce the experimental data.
- Published
- 2015
39. Jet-cooled diode laser spectrum and FTIR integrated band intensities of CF3Br: rovibrational analysis of 2v5 and v2+v3 bands near 9 micron and cross-section measurements in the 450-2500 cm-1 region
- Author
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Santi Giorgianni, A. Pietropolli Charmet, Agostino Baldacci, Nicola Tasinato, Paolo Stoppa, Pietropolli Charmet, A., Tasinato, N., Stoppa, P., Baldacci, A., and Giorgianni, S.
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Infrared ,Chemistry ,Biophysics ,Analytical chemistry ,Rotational temperature ,Natural abundance ,Rotational–vibrational spectroscopy ,Condensed Matter Physics ,Laser ,Molecular physics ,law.invention ,law ,Isotopologue ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Molecular Biology ,Diode ,Settore CHIM/02 - Chimica Fisica - Abstract
The high resolution (up to 0.0007 cm−1) infrared diode laser spectrum of CF3Br (Halon 1301) with natural isotopic abundance has been investigated in the region 1090–1130 cm−1, characterized by the presence of the 2ν5 and ν2 + ν3 absorptions and several weaker hot bands. The rovibrational analysis of the data, obtained employing a slit-jet system (rotational temperature of about 50 K) together with those recorded at 200 K, led to a complete and accurate set of spectroscopic constants for the bands of both the bromine isotopologues. Integrated band intensities have been obtained for all the absorptions in the spectral range 450–2500 cm−1. The high resolution data and information concerning the cross-sections of this molecule can be useful for its remote sensing and for better modelling its contribution to global warming.
- Published
- 2008
40. ATIRS package: A program suite for the rovibrational analysis of infrared spectra of asymmetric top molecules
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Nicola Tasinato, A. Pietropolli Charmet, Paolo Stoppa, Tasinato, N., Pietropolli Charmet, A., and Stoppa, P.
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Software suite ,Infrared ,Computer science ,business.industry ,Suite ,Infrared spectroscopy ,Rotational–vibrational spectroscopy ,CALPGM graphical interface, Computer assisted rovibrational analysis, Interactive Loomis-Wood assignment scheme, IR spectra simulation software ,Atomic and Molecular Physics, and Optics ,Spectral line ,Molecule ,Physical and Theoretical Chemistry ,business ,Algorithm ,Spectroscopy ,Graphical user interface - Abstract
Nowadays high-resolution infrared spectra can be recorded quite easily and therefore it has become important to assist the rovibrational analysis, especially the assignment step, that is still fraught with many problems in the presence of perturbation effects. In this article we provide a description of ATIRS, a complete software suite developed for assisting in the rotational investigation of vibrational bands of asymmetric top molecules. This package uses the Pickett’s CALPGM suite for fitting transitions and predicting line positions and is composed by three stand-alone applications: (1) Visual Loomis–Wood for the assignment of spectral lines based on Loomis–Wood type diagrams; (2) Visual CALPGM, a new graphical interface to Pickett’s programs SPFIT and SPCAT; (3) Visual Spectra Simulator for the simulation of spectra. The graphical interface to the CALPGM suite is developed for asymmetric rotors. The main feature of this application is to avoid the use of the parameter codes that are here replaced employing the well known parameter names or symbols. Highlighting the regular transition sequences, Visual Loomis–Wood assists in the assignment of the spectral lines. It visualizes the description of a transition and the assignment can be simply done by mouse-clicking on the diagram; moreover its display mode feature lets to check the experimental spectrum in which all the assigned lines together with their description are reported. Visual Spectra Simulator provides a simple and functionally application that, using the calculated frequencies and intensities given by SPCAT, simulates the high-resolution infrared spectrum and compare it to the experimental one. ATIRS, freely available to the spectroscopic community, is designed to be easy to use and presents a standard graphical interface; being based on the CALPGM package it can handle forbidden transitions and perturbations among many states.
- Published
- 2007
41. Theoretical investigation of the OH-initiated atmospheric degradation mechanism of CX 2 CHX (X = H, F, Cl) by advanced quantum chemical and transition state theory methods.
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Rais N, Salta Z, and Tasinato N
- Abstract
Halogenated olefins are anthropogenic compounds with many industrial applications but at the same time raising many environmental and health concerns. Gas-phase electrophilic addition of the OH radical to the olefinic CC bond represents the primary sink for these chemicals in the atmosphere, with the degree and type of halogenation playing a significant role in their overall reactivity. In this work, we present a theoretical investigation of the reaction mechanisms and kinetics for the reactions between the OH radical and CH
2 CH2 (ethylene, ETH), CF2 CHF (trifluoroethylene, TFE) and CCl2 CHCl (trichloroethylene, TCE), simulated by state-of-the-art protocols and methods, with the aim of providing a detailed interpretation of the available experimental results, as well as new data of relevance to tropospheric chemistry. Specifically, potential energy surfaces (PESs) are obtained using the jun-Cheap (jChS) composite scheme, whereas temperature and pressure dependent rate coefficients and product distributions in the 100-600 K temperature range are calculated within the Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) framework. The rates for barrierless channels are obtained from variable reaction coordinate-variational transition state theory (VRC-VTST) combined with the two transition state model. While the reactions with ETH and TFE proceed mainly via the formation of addition adducts at P = 1 atm and T = 298 K, the dominant channel for TCE is the Cl-elimination reaction. Global rate constants for the two halogenated olefins, TFE and TCE, are found to be pressure-independent, contrary to the case of ETH. The computed rate constants, as well as their temperature and pressure dependence, are in remarkable agreement with the available experimental data, and they are used to derive atmospheric lifetimes ( τ ) for both TFE and TCE as a function of altitude ( h ) in the atmosphere, by taking into account variations in the rate coefficients ( k ( T , P )) and [OH] concentration.- Published
- 2024
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42. Energetics of the OH radical H-abstraction reactions from simple aldehydes and their geminal diol forms.
- Author
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Salta Z, Schaefer T, Tasinato N, Kieninger M, Katz A, Herrmann H, and Ventura ON
- Abstract
Context: Carbonyl compounds, especially aldehydes, emitted to the atmosphere, may suffer hydration in aerosols or water droplets in clouds. At the same time, they can react with hydroxyl radicals which may add or abstract hydrogen atoms from these species. The interplay between hydration and hydrogen abstraction is studied using density functional and quantum composite theoretical methods, both in the gas phase and in simulated bulk water. The H-abstraction from the aldehydic and geminal diol forms of formaldehyde, acetaldehyde, glycolaldehyde, glyoxal, methylglyoxal, and acrolein is studied to determine whether the substituent has any noticeable effect in the preference for the abstraction of one form or another. It is found that abstraction of the H-atom adjacent to the carbonyl group gives a more stable radical than same abstraction from the geminal diol in the case of formaldehyde, acetaldehyde, and glycolaldehyde. The presence of a delocalizing group in the C
α (a carbonyl group in glyoxal and methylglyoxal, and a vinyl group in acrolein), reverts this trend, and now the abstraction of the H-atom from the geminal diol gives more stable radicals. A further study was conducted abstracting hydrogen atoms from the other different positions in the species considered, both in the aldehydic and geminal diol forms. Only in the case of glycolaldehyde, the radical formed by H-abstraction from the -CH2 OH group is more stable than any of the other radical species. Abstraction of the hydrogen atom in one of the hydroxyl groups in the geminal diol is equivalent to the addition of the• OH radical to the aldehyde. It leads, in some cases, to decomposition into a smaller radical and a neutral molecule. In these cases, some interesting theoretical differences are observed between the results in gas phase and (simulated) bulk solvent, as well as with respect to the method of calculation chosen., Methods: DFT (M06-2X, B2PLYP, PW6B95), CCSD(T), and composite (CBS-QB3, jun-ChS, SCVECV-f12) methods using Dunning basis sets and extrapolation to the CBS limit were used to study the energetics of closed shell aldehydes in their keto and geminal-diol forms, as well as the radical derived from them by hydrogen abstraction. Both gas phase and simulated bulk solvent calculations were performed, in the last case using the Polarizable Continuum Model., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)- Published
- 2024
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43. A new chapter in the never ending story of cycloadditions: The puzzling case of SO 2 and acetylene.
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Salta Z, Ventura ON, Rais N, Tasinato N, and Barone V
- Abstract
A comprehensive study of the different classes of cycloaddition reactions ([3+2], [2+2], and [2+1]) of SO
2 to acetylene and ethylene has been performed using density functional theory (DFT) and composite wavefunction methods. The [3+2] cycloaddition reaction, that was previously explored in the context of the cycloaddition of thioformaldehyde S-methylide (TSM) to ethylene and acetylene, proceeds in a concerted way to the formation of stable heterocycles. In this paper, we extend our study to the [2+2] and [2+1] cycloadditions of SO2 to acetylene, which would produce 1,1-oxathiete-2-oxide and thiirene-1,1-dioxide, respectively. One of the main conclusions is that cyclic 1,1-oxathiete-2-oxide can open through a relatively easy breaking of the SO single bond and rearrange toward sulfinyl acetaldehyde (SA). The SA molecule can easily undergo several internal rearrangements, which eventually lead to sulfenic acid and sulfoxide derivatives of ethenone, 1,2,3-dioxathiole, and CO plus sulfinylmethane. The most probable path, however, produces 2-thioxoacetic acid, whose derivatives (or those of the corresponding acetate) are usually obtained by Willgerodt-Kindler-type sulfuration of acetates. This product can in turn decompose, leading to the final products CO2 and H2 CS. Comparison of this decomposition path with that of 2-amino-2-thioxoacetic acid shows that the process occurs through different H-transfer processes., (© 2024 Wiley Periodicals LLC.)- Published
- 2024
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44. Reliable Gas Phase Reaction Rates at Affordable Cost by Means of the Parameter-Free JunChS-F12 Model Chemistry.
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Barone V, Lupi J, Salta Z, and Tasinato N
- Abstract
A recently developed strategy for the computation at affordable cost of reliable barrier heights ruling reactions in the gas phase (junChS, [Barone, V.; J. Chem. Theory Comput. 2021, 17, 4913-4928]) has been extended to the employment of explicitly correlated (F12) methods. A thorough benchmark based on a wide range of prototypical reactions shows that the new model (referred to as junChS-F12), which employs cost-effective revDSD-PBEP86-D3(BJ) reference geometries, has an improved performance with respect to its conventional counterpart and outperforms the most well-known model chemistries without the need of any empirical parameter and at an affordable computational cost. Several benchmarks show that revDSD-PBEP86-D3(BJ) structures and force fields provide zero point energies and thermal contributions, which can be confidently used, together with junChS-F12 electronic energies, for obtaining accurate reaction rates in the framework of the master equation approach based on the ab initio transition-state theory.
- Published
- 2023
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45. Toward Spectroscopic Accuracy for the Structures of Large Molecules at DFT Cost: Refinement and Extension of the Nano-LEGO Approach.
- Author
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Barone V, Ceselin G, Lazzari F, and Tasinato N
- Abstract
The SE100 database collecting accurate equilibrium geometries of medium size molecules obtained by the semiexperimental (SE) approach has been extended to species containing Br and I atoms. This has allowed the determination of accurate linear regressions between DFT and SE values for all the main bonds and angles involving H, B, C, N, O, F, P, S, Cl, Br, and I atoms. An improved Nano-LEGO tool has been developed, which is based on suitable hybrid and double hybrid functionals and combines in a fully coherent way the templating molecule and linear regression approaches. A number of case studies show that the new Nano LEGO tool provides geometrical parameters on par with state-of-the-art composite wave function methods, but can be routinely applied to medium- to large-size molecules. The accuracy reached for structural parameters is mirrored on rotational constants that can be predicted with an average error within 0.2%.
- Published
- 2023
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46. Correcting the Experimental Enthalpies of Formation of Some Members of the Biologically Significant Sulfenic Acids Family.
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Ventura ON, Segovia M, Vega-Teijido M, Katz A, Kieninger M, Tasinato N, and Salta Z
- Subjects
- Proteins, Sulfhydryl Compounds chemistry, Thermodynamics, Cysteine chemistry, Sulfenic Acids metabolism
- Abstract
Sulfenic acids are important intermediates in the oxidation of cysteine thiol groups in proteins by reactive oxygen species. The mechanism is influenced heavily by the presence of polar groups, other thiol groups, and solvent, all of which determines the need to compute precisely the energies involved in the process. Surprisingly, very scarce experimental information exists about a very basic property of sulfenic acids, the enthalpies of formation. In this Article, we use high level quantum chemical methods to derive the enthalpy of formation at 298.15 K of methane-, ethene-, ethyne-, and benzenesulfenic acids, the only ones for which some experimental information exists. The methods employed were tested against well-known experimental data of related species and extensive CCSD(T) calculations. Our best results consistently point out to a much lower enthalpy of formation of methanesulfenic acid, CH
3 SOH (Δf H0 (298.15 K ) = -35.1 ± 0.4 kcal mol-1 ), than the one reported in the NIST thermochemical data tables. The enthalpies of formation derived for ethynesulfenic acid, HC≡CSOH, +32.9 ± 1.0 kcal/mol, and benzenesulfenic acid, C6 H5 SOH, -2.6 ± 0.6 kcal mol-1 , also differ markedly from the experimental values, while the enthalpy of formation of ethenesulfenic acid CH2 CHSOH, not available experimentally, was calculated as -11.2 ± 0.7 kcal mol-1 .- Published
- 2022
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47. In Vitro and In Silico Vibrational-Rotational Spectroscopic Characterization of the Next-Generation Refrigerant HFO-1123.
- Author
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Tasinato N, Pietropolli Charmet A, Ceselin G, Salta Z, and Stoppa P
- Abstract
Very short-lived substances have recently been proposed as replacements for hydrofluorocarbons (HFCs), in turn being used in place of ozone-depleting substances, in refrigerant applications. In this respect, hydro-fluoro-olefins (HFOs) are attracting particular interest because, due to their reduced global warming potential, they are supposed to be environmentally friendlier. Notwithstanding this feature, they represent a new class of compounds whose spectroscopic properties and reactivity need to be characterized to allow their atmospheric monitoring and to understand their environmental fate. In the present work, the structural, vibrational, and ro-vibrational properties of trifluorothene (HFO-1123, F
2 C = CHF) are studied by state-of-the-art quantum chemical calculations. The equilibrium molecular structure has an expected error within 2 mÅ and 0.2° for bond lengths and angles, respectively. This represents the first step toward the computation of highly accurate rotational constants for both the ground and first excited fundamental vibrational levels, which reproduce the available experimental data well within 0.1%. Centrifugal distortion parameters and vibrational-rotational coupling terms are computed as well and used to solve some conflicting experimental results. Simulation of the vibrational transition frequencies and intensities beyond the double harmonic approximation and up to three quanta of vibrational excitation provides insights into the couplings ruling the vibrational dynamics and guides the characterization of the gas-phase infrared spectrum experimentally recorded in the range of 200-5000 cm-1 . The full characterization of the IR features is completed with the experimental determination of the absorption cross sections over the 400-5000 cm-1 region from which the radiative forcing and global warming potential of HFO-1123 are derived.- Published
- 2022
- Full Text
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48. Dipolar 1,3-cycloaddition of thioformaldehyde S-methylide (CH 2 SCH 2 ) to ethylene and acetylene. A comparison with (valence) isoelectronic O 3 , SO 2 , CH 2 OO and CH 2 SO.
- Author
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Salta Z, Vega-Teijido M, Katz A, Tasinato N, Barone V, and Ventura ON
- Abstract
Methods rooted in the density functional theory and in the coupled cluster ansatz were employed to investigate the cycloaddition reactions to ethylene and acetylene of 1,3-dipolar species including ozone and the derivatives issued from replacement of the central oxygen atom by the valence-isoelectronic sulfur atom, and/or of one or both terminal oxygen atoms by the isoelectronic CH
2 group. This gives rise to five different 1,3-dipolar compounds, namely ozone itself (O3 ), sulfur dioxide (SO2 ), the simplest Criegee intermediate (CH2 OO), sulfine (CH2 SO), and thioformaldehyde S-methylide (CH2 SCH2 , TSM). The experimental and accurate theoretical data available for some of those molecules were employed to assess the accuracy of two last-generation composite methods employing conventional or explicitly correlated post-Hartree-Fock contributions (jun-Cheap and SVECV-f12, respectively), which were then applied to investigate the reactivity of TSM. The energy barriers provided by both composite methods are very close (the average values for the two composite methods are 7.1 and 8.3 kcal mol-1 for the addition to ethylene and acetylene, respectively) and comparable to those ruling the corresponding additions of ozone (4.0 and 7.7 kcal mol-1 , respectively). These and other evidences strongly suggest that, at least in the case of cycloadditions, the reactivity of TSM is similar to that of O3 and very different from that of SO2 ., (© 2022 Wiley Periodicals LLC.)- Published
- 2022
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49. Gliding on Ice in Search of Accurate and Cost-Effective Computational Methods for Astrochemistry on Grains: The Puzzling Case of the HCN Isomerization.
- Author
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Baiano C, Lupi J, Barone V, and Tasinato N
- Abstract
The isomerization of hydrogen cyanide to hydrogen isocyanide on icy grain surfaces is investigated by an accurate composite method (jun-Cheap) rooted in the coupled cluster ansatz and by density functional approaches. After benchmarking density functional predictions of both geometries and reaction energies against jun-Cheap results for the relatively small model system HCN···(H
2 O)2 , the best performing DFT methods are selected. A large cluster containing 20 water molecules is then employed within a QM/QM' approach to include a realistic environment mimicking the surface of icy grains. Our results indicate that four water molecules are directly involved in a proton relay mechanism, which strongly reduces the activation energy with respect to the direct hydrogen transfer occurring in the isolated molecule. Further extension of the size of the cluster up to 192 water molecules in the framework of a three-layer QM/QM'/MM model has a negligible effect on the energy barrier ruling the isomerization. Computation of reaction rates by the transition state theory indicates that on icy surfaces, the isomerization of HNC to HCN could occur quite easily even at low temperatures thanks to the reduced activation energy that can be effectively overcome by tunneling.- Published
- 2022
- Full Text
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50. Accurate Quantum Chemical Spectroscopic Characterization of Glycolic Acid: A Route Toward its Astrophysical Detection.
- Author
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Ceselin G, Salta Z, Bloino J, Tasinato N, and Barone V
- Subjects
- Glycolates, Humans, Molecular Conformation, Spectrum Analysis, Quantum Theory, Vibration
- Abstract
The first step to shed light on the abiotic synthesis of biochemical building blocks, and their further evolution toward biological systems, is the detection of the relevant species in astronomical environments, including earthlike planets. To this end, the species of interest need to be accurately characterized from structural, energetic, and spectroscopic viewpoints. This task is particularly challenging when dealing with flexible systems, whose spectroscopic signature is ruled by the interplay of small- and large-amplitude motions (SAMs and LAMs, respectively) and is further tuned by the conformational equilibrium. In such instances, quantum chemical (QC) calculations represent an invaluable tool for assisting the interpretation of laboratory measurements or even observations. In the present work, the role of QC results is illustrated with reference to glycolic acid (CH
2 OHCOOH), a molecule involved in photosynthesis and plant respiration and a precursor of oxalate in humans, which has been detected in the Murchison meteorite but not yet in the interstellar medium or in planetary atmospheres. In particular, the equilibrium structure of the lowest-energy conformer is derived by employing the so-called semiexperimental approach. Then, accurate yet cost-effective QC calculations relying on composite post-Hartree-Fock schemes and hybrid coupled-cluster/density functional theory approaches are used to predict the structural and ro-vibrational spectroscopic properties of the different conformers within the framework of the second-order vibrational perturbation theory. A purposely tailored discrete variable representation anharmonic approach is used to treat the LAMs related to internal rotations. The computed spectroscopic data, particularly those in the infrared region, complement the available experimental investigations, thus enhancing the possibility of an astronomical detection of this molecule.- Published
- 2022
- Full Text
- View/download PDF
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