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7. Atomistic and electronic structure of bimetallic cobalt/rhenium clusters from density functional theory calculations.

Author

Bakken, Vebjørn and Swang, Ole

Subjects
*COBALT alloys, *METAL clusters, *DENSITY functionals, *ELECTRONIC structure, *ATOMIC structure, *LAMINATED metals
Abstract

We have carried out computational density functional investigations of CoIReJ (J=0,1,2; I+J=14) metal atom clusters. Through thorough optimization of geometry, spin polarization, and electronic configuration, the most stable structures for each cluster have been identified. While the global minima are found to be well defined and energetically well separated from other local minima, the study reveals a plethora of different structures and symmetries only moderately higher in energy. A key point of interest is the effect of doping the cobalt clusters with rhenium. Aside from significant structural reorganizations, rhenium is found to stabilize the clusters and couple down the spin. Furthermore, the most stable clusters comprise highly coordinated rhenium and, in the case of Co12Re2, Re–Re bonding. Our results are compared to earlier experimental and computational data. [ABSTRACT FROM AUTHOR]

Published
2008
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8. Calculation of electric dipole hypershieldings at the nuclei in the Hellmann–Feynman approximation.

Author

Soncini, Alessandro, Lazzeretti, Paolo, Bakken, Vebjørn, and Helgaker, Trygve

Subjects
MOLECULES, HARTREE-Fock approximation, VIBRATION (Mechanics), ELECTRIC fields, PHYSICS, SUM rules (Physics)
Abstract

The third-rank electric hypershieldings at the nuclei of four small molecules have been evaluated at the Hartree–Fock level of theory in the Hellmann–Feynman approximation. The nuclear electric hypershieldings are closely related to molecular vibrational absorption intensities and a generalization of the atomic polar tensors (expanded in powers of the electric field strength) is proposed to rationalize these intensities. It is shown that the sum rules for rototranslational invariance and the constraints imposed by the virial theorem provide useful criteria for basis-set completeness and for near Hartree–Fock quality of nuclear shieldings and hypershieldings evaluated in the Hellmann–Feynman approximation. Twelve basis sets of different size and quality have been employed for the water molecule in an extended numerical test on the practicality of the proposed scheme. The best results are obtained with the R12 and R12+ basis sets, designed for the calculation of electronic energies by the explicitly correlated R12 method. The R12 basis set is subsequently used to investigate three other molecules, CO, N[sub 2], and NH[sub 3], verifying that the R12 basis consistently performs very well. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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9. The efficient optimization of molecular geometries using redundant internal coordinates.

Author

Bakken, Vebjørn and Helgaker, Trygve

Subjects
*MOLECULES, *MATHEMATICAL optimization, *COORDINATES
Abstract

The optimization of ab initio molecular geometries is discussed. Based on comparisons of 30 minimizations and 15 saddle-point optimizations, the most efficient combination of coordinate system, approximate and exact Hessians, and step control is determined. Use of a proposed set of extra-redundant internal coordinates is shown to reduce the number of geometry steps significantly relative to the use of redundant coordinates. Various update schemes are tested for minimum and saddle-point optimizations, including combination formulas. The complete expressions for the first and second derivatives of the Wilson B matrix are presented, thereby avoiding the need to calculate this by finite-difference methods. The presented scheme appears to be the most efficient, robust and generally applicable scheme to date. [ABSTRACT FROM AUTHOR]

Published
2002
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10. The Dalton quantum chemistry program system

Author

Aidas, Kestutis, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linus, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pal, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa., Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thomas, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andreas, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Anders, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvinas, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., Sanchez de Merás, Alfredo, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Aidas, Kestuti, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linu, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pål, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thoma, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa, Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thoma, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andrea, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Ander, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvina, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., de Merás, Alfredo Sánchez, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Dipartimento di Chimica, Università degli Studi di Ferrara (UniFE), Centre for Theoretical and Computational Chemistry [Oslo] (CTCC), Department of Chemistry [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Department of Physics, Chemistry and Biology, Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratory of the Department of Oncology (DEPARTMENT OF ONCOLOGY), Herlev and Gentofte Hospital, Norwegian Meteorological Institute [Oslo] (MET), Teoretisk Kemi, Aarhus University [Aarhus], Centre for Biodiversity Dynamics, Norwegian University of Science and Technology [Trondheim] (NTNU), Norwegian University of Science and Technology (NTNU)-Norwegian University of Science and Technology (NTNU), Karlsruhe Institute of Technology (KIT), Department of Theoretical Chemistry, University Düsseldorf, Department of Mathematics, Tokyo University of Science, Institut Jean-Pierre Bourgin (IJPB), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Department of Environmental Engineering, Technical University of Denmark [Lyngby] (DTU), Computer Services Networks and Systems, Università degli Studi di Modena e Reggio Emilia (UNIMORE), Hammersmith Hospital, Imperial College, London, Department of Haematology, Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Centre for Theoretical and Computational Chemistry, University of Tromsø (UiT), Department of Electronics Materials and Devices, Ivanovo State University of Chemistry and Technology, Department of Chemistry [Copenhagen], Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California [San Diego] (UC San Diego), University of California-University of California, School of Chemistry, University of Nottingham, UK (UON), Theoretical Chemistry, Royal Institute of Technology [Stockholm] (KTH ), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Norwegian Meteorological Institute, Bakke, Vebjørn, Hjertenaes, Eirik, Høyvik, Ida Marie, Jensen, Hans Jørgen A. a., Kjaergaard, Thoma, Lutnaes, Ola B., Sánchez de Merás, Alfredo, Sylvester Hvid, Kristian O., Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials Chemistry2506 Metals and Alloys, Software Focus, Ab initio electronic structure methods structure methods, ab initio calculations, VDP::Mathematics and natural science: 400::Chemistry: 440::Theoretical chemistry, quantum chemistry: 444, Computer Science Applications1707 Computer Vision and Pattern Recognition, Quantum chemistry program, Ab-initio methods, Scientific Software, Quantum Chemistry, Molecular properties, Biochemistry, Algorithms, [Electronic Structure Theory], Algorithm, Molecular propertie, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Computational Chemistry, Computational Mathematic, Faculty of Science, Physical and Theoretical Chemistry, VDP::Matematikk og Naturvitenskap: 400::Kjemi: 440::Teoretisk kjemi, kvantekjemi: 444
Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self-consistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms. © 2013 John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, (CC BY-NC-ND 3.0)

Published
2014

11. The Dalton quantum chemistry program system

Author

Aidas, Kestudis, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linus, Chistiansen, Ove, Coriani, Sonia, Dahle, Pål, Dalskov, Eric K., Ekström, Ulf, Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Kalkier, Asger, Hättig, Chistof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Melo, Juan Ignacio, and Provasi, Patricio Federico

Subjects
purl.org/becyt/ford/1 [https], COMPUTATIONAL, Física Atómica, Molecular y Química, MOLECULAR, DALTON, Ciencias Físicas, PROGRAM, purl.org/becyt/ford/1.3 [https], CIENCIAS NATURALES Y EXACTAS, PROPERTIES
Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational selfconsistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantummechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms. Fil: Aidas, Kestudis. Vilnius University; Lituania Fil: Angeli, Celestino. Universita Di Ferrara; Italia Fil: Bak, Keld L.. University Aarhus; Dinamarca Fil: Bakken, Vebjørn. University Of Oslo; Noruega Fil: Bast, Radovan. KTH Royal Institute of Techology; Suecia Fil: Boman, Linus. EMGS ASA; Noruega Fil: Chistiansen, Ove. Universita Di Ferrara; Italia Fil: Coriani, Sonia. Universita Degli Studi Di Trieste; Italia Fil: Dahle, Pål. Norwegian Computer Center; Noruega Fil: Dalskov, Eric K.. Systematic; Dinamarca Fil: Ekström, Ulf. University Of Oslo; Noruega Fil: Enevoldsen, Thomas. University of Southern Denmark; Dinamarca Fil: Eriksen, Janus J.. University Aarhus; Dinamarca Fil: Ettenhuber, Patrick. University Aarhus; Dinamarca Fil: Fernández, Berta. Universidad de Santiago de Compostela; España Fil: Ferrighi, Lara. University of Norway; Noruega Fil: Fliegl, Heike. University Of Oslo; Noruega Fil: Frediani, Luca. University of Norway; Noruega Fil: Hald, Kasper. Danske Bank; Dinamarca Fil: Kalkier, Asger. CSC Scandihealth; Dinamarca Fil: Hättig, Chistof. Ruhr-universität Bochum; Alemania Fil: Heiberg, Hanne. Norwegian Meterological Institute; Noruega Fil: Helgaker, Trygve. University Of Oslo; Noruega Fil: Hennum, Alf Christian. Norwegian Defence Research Establishment; Noruega Fil: Hettema, Hinne. The University Of Auckland; Nueva Zelanda Fil: Hjertenæs, Eirik. Norwegian University of Science and Technology; Noruega Fil: Høst, Stinne. University Aarhus; Dinamarca Fil: Melo, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Provasi, Patricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnologica; Argentina

Published
2014

12. Insights into the dynamics of evaporation and proton migration in protonated water clusters from large-scale born-oppenheimer direct dynamics.

Author

Rybkin, Vladimir V., Simakov, Anton O., Bakken, Vebjørn, Reine, Simen, Kjærgaard, Thomas, Helgaker, Trygve, and Uggerud, Einar

Subjects
MOLECULAR dynamics, EVAPORATION (Chemistry), PROTON transfer reactions, WATER clusters, BORN-Oppenheimer approximation, ELECTRONIC structure, FEASIBILITY studies, REACTION mechanisms (Chemistry)
Abstract

Large-scale on-the-fly Born-Oppenheimer molecular dynamics simulations using recent advances in linear scaling electronic structure theory and trajectory integration techniques have been performed for protonated water clusters around the magic number (H2O) nH+, for n = 20 and 21. Besides demonstrating the feasibility and efficiency of the computational approach, the calculations reveal interesting dynamical details. Elimination of water molecules is found to be fast for both cluster sizes but rather insensitive to the initial geometry. The water molecules released acquire velocities compatible with thermal energies. The proton solvation shell changes between the well-known Eigen and Zundel motifs and is characterized by specific low-frequency vibrational modes, which have been quantified. The proton transfer mechanism largely resembles that of bulk water but one interesting variation was observed. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2013
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14. The Dalton quantum chemistry program system.

Author

Aidas K, Angeli C, Bak KL, Bakken V, Bast R, Boman L, Christiansen O, Cimiraglia R, Coriani S, Dahle P, Dalskov EK, Ekström U, Enevoldsen T, Eriksen JJ, Ettenhuber P, Fernández B, Ferrighi L, Fliegl H, Frediani L, Hald K, Halkier A, Hättig C, Heiberg H, Helgaker T, Hennum AC, Hettema H, Hjertenæs E, Høst S, Høyvik IM, Iozzi MF, Jansík B, Jensen HJ, Jonsson D, Jørgensen P, Kauczor J, Kirpekar S, Kjærgaard T, Klopper W, Knecht S, Kobayashi R, Koch H, Kongsted J, Krapp A, Kristensen K, Ligabue A, Lutnæs OB, Melo JI, Mikkelsen KV, Myhre RH, Neiss C, Nielsen CB, Norman P, Olsen J, Olsen JM, Osted A, Packer MJ, Pawlowski F, Pedersen TB, Provasi PF, Reine S, Rinkevicius Z, Ruden TA, Ruud K, Rybkin VV, Sałek P, Samson CC, de Merás AS, Saue T, Sauer SP, Schimmelpfennig B, Sneskov K, Steindal AH, Sylvester-Hvid KO, Taylor PR, Teale AM, Tellgren EI, Tew DP, Thorvaldsen AJ, Thøgersen L, Vahtras O, Watson MA, Wilson DJ, Ziolkowski M, and Agren H

Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, Møller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms.

Published
2014
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15. An efficient density-functional-theory force evaluation for large molecular systems.

Author

Reine S, Krapp A, Iozzi MF, Bakken V, Helgaker T, Pawłowski F, and Sałek P

Abstract

An efficient, linear-scaling implementation of Kohn-Sham density-functional theory for the calculation of molecular forces for systems containing hundreds of atoms is presented. The density-fitted Coulomb force contribution is calculated in linear time by combining atomic integral screening with the continuous fast multipole method. For higher efficiency and greater simplicity, the near-field Coulomb force contribution is calculated by expanding the solid-harmonic Gaussian basis functions in Hermite rather than Cartesian Gaussians. The efficiency and linear complexity of the molecular-force evaluation is demonstrated by sample calculations and applied to the geometry optimization of a few selected large systems.

Published
2010
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16. Synthesis, structure, and antimycobacterial activity of 6-[1(3H)-isobenzofuranylidenemethyl]purines and analogs.

Author

Braendvang M, Bakken V, and Gundersen LL

Subjects
Animals, Antitubercular Agents chemical synthesis, Cell Survival drug effects, Chlorocebus aethiops, Crystallography, X-Ray, Microbial Sensitivity Tests, Models, Molecular, Purines chemical synthesis, Structure-Activity Relationship, Vero Cells, Antitubercular Agents chemistry, Antitubercular Agents pharmacology, Mycobacterium tuberculosis drug effects, Purines chemistry, Purines pharmacology, Tuberculosis drug therapy
Abstract

6-Benzofuryl-, styryl, benzyl, and furfurylpurines as well as 6-[1(3H)-isobenzofuranylidenemethyl]purines have been synthesized and their activities against Mycobacterium tuberculosis (Mtb) determined. Several compounds displayed profound antimycobacterial activity in combination with low toxicity towards mammalian cells. NMR and X-ray crystallography were employed to determine the detailed structures and the results were supported by quantum chemical calculations.

Published
2009
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17. Models of fragmentations induced by electron attachment to protonated peptides.

Author

Bakken V, Helgaker T, and Uggerud E

Subjects
Peptide Fragments chemistry, Electrons, Models, Chemical, Peptides chemistry, Protons, Spectrometry, Mass, Electrospray Ionization, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Abstract

Invoking a number of theoretical levels ranging from HF/STO-3G to CCSD(T)/aug-cc-pVQZ, we have made a detailed survey of six potential energy surfaces (NH4+, NH4*, [CH3CONHCH3]H+, [CH3CONHCH3]H*, [HCONHCH2CONH2]H+, [HCONHCH2CONH2]H*). In conjunction with this, ab inito direct dynamics calculations have been conducted, tracing out several hundred reaction trajectories to reveal details of the electron-capture dissociation mechanism. The model calculations suggest the possibility of a bimodal pattern where some of the radicals, formed upon recombination, dissociate almost directly within one picosecond, the remaining radicals being subject to complete energy redistribution with a subsequent dissociation occurring at the microsecond timescale. Both processes give rise to c and z backbone fragments, resulting from cleavage of N-Calpha bonds of the peptide chain.

Published
2004
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18. The Oxidative Power of Protonated Hydrogen Peroxide The work was supported by NFR (The Norwegian Research Council). The authors thank Drs. Gustav Bojesen and Steen Hammerum (University of Copenhagen) for generous cooperation, and Prof. H. Bernhard Schlegel (Wayne State University) for computer time and the use of a development version of Gaussian 98. Helpful suggestions from Profs. Terry B. McMahon (Waterloo University) and Michael T. Bowers (UC, Santa Barbara) are acknowledged.

Author

Leere Øiestad ÅM, Petersen AC, Bakken V, Vedde J, and Uggerud E

Published
2001

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