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6. Low-lying electronic states of the Ti2 dimer: Electronic absorption spectroscopy in rare gas matrices in concert with quantum chemical calculations.

Author

Hübner, O., Himmel, H.-J., Manceron, L., and Klopper, W.

Subjects
TITANIUM spectra, ABSORPTION spectra, QUANTUM chemistry, DIMERS, NOBLE gases, EXCITED state chemistry
Abstract

Absorption spectra were measured for Ti2 in Ne and Ar matrices. The spectra give evidence for several electronic transitions in the region between 4000 and 10 000 cm-1 and provide important information about some excited electronic states of Ti2 in proximity to the ground state. The vibrational fine structure measured for these transitions allowed to calculate the force constants and the anharmonicity of the potential energy curves of the excited states, and to estimate changes in the internuclear Ti-Ti distances relative to the electronic ground state. The quantum chemical studies confirm the previously suggested 3Δg state as the ground state of Ti2. The equilibrium bond distance is calculated to be 195.4 pm. The calculated harmonic frequency of 432 cm-1 is in good agreement with the experimental value of 407.0 cm-1. With the aid of the calculations it was possible to assign the experimentally observed transitions in the region between 4000 and 10 000 cm-1 to the 1 3Πu←3Δg, 1 3[uppercase_phi_synonym]u←3Δg, 2 3Πu←3Δg, 2 3[uppercase_phi_synonym]u←3Δg, and 3Δu←3Δg excitations (in the order of increasing energy). The calculated relative energies and harmonic frequencies are in pleasing agreement with the experimentally obtained values, with deviations of less than 5% and 2%, respectively. The bond distances estimated on the basis of the experimental spectra tally satisfactorily with the predictions of our calculations. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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7. Experiences with the Cyber 205 for Quantum Chemical Calculations

Author

Kutzelnigg, W., Schindler, M., Klopper, W., Koch, S., Meier, U., Wallmeier, H., Berthier, G., editor, Dewar, M. J. S., editor, Fischer, H., editor, Fukui, K., editor, Hall, G. G., editor, Hinze, J., editor, Jaffé, H. H., editor, Jortner, J., editor, Kutzelnigg, W., editor, Ruedenberg, K., editor, Tomasi, J., editor, and Dupuis, M., editor

Published
1986
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9. Ab initio computations close to the one-particle basis set limit on the weakly bound van der Waals complexes benzene–neon and benzene–argon.

Author

Klopper, W., Lüthi, H. P., Brupbacher, Th., and Bauder, A.

Subjects
*EQUILIBRIUM, *BINDING energy, *BENZENE, *PERTURBATION theory, *DIPOLE moments
Abstract

The equilibrium geometries and binding energies of the van der Waals (vdW) complexes benzene–neon and benzene–argon have been calculated at the level of second-order Mo\ller–Plesset perturbation theory (MP2). Terms linear in the interelectronic distances r12 were used in the MP2 treatment to converge fast to the one-particle basis set limit. This new method, MP2-R12 as implemented in the sore program, was applied with high quality basis sets derived from Dunning’s aug-cc-pVXZ (X=D,T,Q,5) sets. In reward of the efforts to reach the basis set limit, it is found that the calculated binding energies for the vdW complexes were computed virtually free of a basis set superposition error (BSSE). The key MP2-R12 results are De=154 cm-1 and re=3.32 Å for benzene–neon and De=553 cm-1 and re=3.41 Å for benzene–argon. The permanent dipole moments of the vdW complexes have been computed by finite field perturbation theory. Coupled-cluster calculations of type CCSD(T), although performed with considerably smaller basis sets than the MP2-R12 calculations, show that, to improve the MP2-R12 results, it is inevitable to consider correlation effects due to connected triple excitations which go beyond the MP2 description. © 1994 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
1994
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10. Accurate dissociation energies of two isomers of the 1-naphthol⋅cyclopropane complex

Author

Maity, S, Knochenmuss, R, Holzer, C, Féraud, G, Frey, J, Klopper, W, Leutwyler, S, Maity, S, Knochenmuss, R, Holzer, C, Féraud, G, Frey, J, Klopper, W, and Leutwyler, S

Abstract

The 1-naphthol⋅cyclopropane intermolecular complex is formed in a supersonic jet and investigated by resonant two-photon ionization (R2PI) spectroscopy, UV holeburning, and stimulated emission pumping (SEP)-R2PI spectroscopy. Two very different structure types are inferred from the vibronic spectra and calculations. In the “edge” isomer, the OH group of 1-naphthol is directed towards a C—C bond of cyclopropane, the two ring planes are perpendicular. In the “face” isomer, the cyclopropane is adsorbed on one of the π-aromatic faces of the 1-naphthol moiety, the ring planes are nearly parallel. Accurate ground-state intermolecular dissociation energies D 0 were measured with the SEP-R2PI technique. The D 0(S 0) of the edge isomer is bracketed as 15.35 ± 0.03 kJ/mol, while that of the face isomer is 16.96 ± 0.12 kJ/mol. The corresponding excited-state dissociation energies D 0(S 1) were evaluated using the respective electronic spectral shifts. Despite the D 0(S 0) difference of 1.6 kJ/mol, both isomers are observed in the jet in similar concentrations, so they must be separated by substantial potential energy barriers. Intermolecular binding energies, De, and dissociation energies, D 0, calculated with correlated wave function methods and two dispersion-corrected density-functional methods are evaluated in the context of these results. The density functional calculations suggest that the face isomer is bound solely by dispersion interactions. Binding of the edge isomer is also dominated by dispersion, which makes up two thirds of the total binding energy.

Published
2016

12. In-depth exploration of the photophysics of a trinuclear palladium complex

Author

Schmitt, Y., Chevalier, K., Rupp, F., Becherer, M., Grun, A., Rijs, A.M., Walz, F., Breher, F., Diller, R., Gerhards, M., Klopper, W., Schmitt, Y., Chevalier, K., Rupp, F., Becherer, M., Grun, A., Rijs, A.M., Walz, F., Breher, F., Diller, R., Gerhards, M., and Klopper, W.

Abstract

Contains fulltext : 128388.pdf (publisher's version ) (Open Access)

Published
2014

25. Density-functional calculation of the quadrupole splitting in the 23Na NMR spectrum of the ferric wheel Na@Fe6(tea)6 + for various broken-symmetry states of the Heisenberg spin model.

Author

Bischoff, F. A., Hübner, O., Klopper, W., Schnelzer, L., Pilawa, B., Horvatić, M., and Berthier, C.

Subjects
DENSITY functionals, NUCLEAR magnetic resonance, QUADRUPOLES, DETERMINANTS (Mathematics), ATOMS
Abstract

The quadrupole splitting in the 23Na nuclear magnetic resonance (NMR) spectrum of the hexanuclear ferric wheel Na@Fe6(tea)6 + has been computed via an evaluation of the electric-field gradient (EFG) at the Na nucleus in the framework of density-functional theory (DFT). The simulated spectrum is compared with experimental data. A total of 26 = 64 Kohn-Sham determinants (a number that reduces to eight symmetry-unique determinants due to the high S6 symmetry of the ferric wheel) with six localised high-spin Fe(III) centres (S = 5/2) could be optimised in a self-consistent manner, and the corresponding DFT energies of all of these (broken-symmetry) determinants coincide almost perfectly according to the Ising Hamiltonian solutions, especially when the energy is computed from the B3LYP functional. The EFG at the Na atom does not depend much on the specific Kohn-Sham determinant but depends on the geometry of the ferric wheel and on the basis set used in the DFT calculations (particularly with regard to the atomic functions on the Na atom). [ABSTRACT FROM AUTHOR]

Published
2007
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26. Molecular Hydrogen Interaction with IRMOF-1:  A Multiscale Theoretical Study

Author

Klontzas, E., Mavrandonakis, A., Froudakis, G.E, Carissan, Y., and Klopper, W.

Abstract

By means of ab initio quantum chemical techniques, the interaction of molecular hydrogen with the first member of the IRMOF family is explored. Many different models and computational schemes, ranging from second-order Møller−Plesset perturbation theory (MP2) to density functional theory (DFT), have been applied in order to find the best model that can describe the IRMOF-1 cell in an accurate manner against moderate computational cost. The results show that the interaction energies of dihydrogen with the inorganic part of the IRMOF-1 are between 0.13 and 0.74 kcal/mol and can be attributed to dipole−induced dipole forces. Basis-set superposition errors are corrected for by the function counterpoise method. The effect of the corrections is large, almost 50% of the uncorrected interaction energy. Furthermore, the correction may shift the minimum of the potential energy curve toward larger distances. The computational approaches used in this study, allow us to find the true minimum of the potential hypersurface. As a conclusion, both organic and inorganic linkers contribute equally to dihydrogen physisorption.

Published
2007
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30. Excited state vibrational coherence in a binuclear metal adduct: wave packet phase dependant molecular fragmentation under variation of ligand size

Author

Kruppa Sebastian Volker, Bäppler Florian, Holzer Christof, Dietrich Fabian, Diller Rolf, Klopper Wim, and Riehn Christoph

Subjects
Physics, QC1-999
Abstract

Ultrafast vibrational coherence with metal-metal stretching mode character is observed for phosphine-bridged d10-d10 complexes of different size, containing the binuclear [Ag2Cl]+ chromophore in an ion trap. Fragmentation pathways are governed by the wave packet's phase.

Published
2019
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35. Time-Resolved Spectroscopy and Electronic Structure of Mono-and Dinuclear Pyridyl-Triazole/DPEPhos-Based Cu(I) Complexes

Author

Grupe, M., Boden, P., Di Martino-Fumo, P., Gui, X., Bruschi, C., Israil, R., Schmitt, M., Nieger, M., Gerhards, M., Klopper, W., Riehn, C., Bizzarri, C., and Diller, R.

Subjects
7. Clean energy
Abstract

The comprehensive results on two mononuclear pyridyl-triazole/DPEPhos based Cu(I) complexes and its extension to their two dinuclear analogues paves the road to addressing the complex coupling of the respective monomeric units, involving various physical and chemical properties as charge, (electronic) structure and (long-lived) excited state properties, relevant for applications. Chemical and spectroscopic characterization of the mononuclear photosensitizers [(DPEPhos)Cu(I)(MPyrT)]$^{0/+}$ (CuL, CuLH) and their dinuclear analogues (Cu$_{2}$L’, Cu$_{2}$L'H$_{2}$), backed by (TD)DFT and high-level GW-Bethe-Salpeter equation calculations, exemplifies the complex influence of charge, nuclearity and structural flexibility on UV-induced photophysical pathways. Ultrafast transient absorption and step-scan FTIR spectroscopy reveal flattening distortion in the triplet state of CuLH as controlled by charge, which also appears to have a large impact on the symmetry of the long-lived triplet states in Cu$_{2}$L’ and Cu$_{2}$L'H$_{2}$. Time-resolved luminescence spectroscopy (solid state), supported by transient photodissociation spectroscopy (gas phase), confirm a lifetime of some tens of μs for the respective triplet states, as well as the energetics of thermally activated delayed luminescence, both being essential parameters for application of these materials based on earth-abundant copper in photocatalysis and luminescent devices.

42. Local Electron Densities and Functional Groups in Quantum Chemistry

Author

Mezey, Paul G., de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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43. Electron Correlation and Reduced Density Matrices

Author

Valdemoro, Carmela, de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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44. Localization via Density Functionals

Author

March, N. H., de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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45. Local Space Approximation Methods for Correlated Electronic Structure Calculations in Large Delocalized Systems that are Locally Perturbed

Author

Kirtman, Bernard, de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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46. Modern Correlation Theories for Extended, Periodic Systems

Author

Sun, Jun-Qiang, Bartlett, Rodney J., de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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47. Extremal Electron Pairs — Application to Electron Correlation, Especially the R12 Method

Author

Klopper, Wim, Kutzelnigg, Werner, Müller, Hendrik, Noga, Jozef, Vogtner, Stefan, de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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48. Ab Initio Modern Valence Bond Theory

Author

Raimondi, Mario, Cooper, David L., de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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49. Extended Geminal Models

Author

Røeggen, I., de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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50. Many-Body Perturbation Theory with Localized Orbitals — Kapuy’s Approach

Author

Pipek, János, Bogár, Ferenc, de Meijere, Armin, editor, Houk, K. N., editor, Kessler, Horst, editor, Lehn, Jean-Marie, editor, Ley, Steven V., editor, Schreiber, Stuart L., editor, Thiem, Joachim, editor, Trost, Barry M., editor, Vögtle, Fritz, editor, Yamamoto, Hisashi, editor, Surján, Péter R., editor, Bartlett, R. J., editor, Bogár, F., editor, Cooper, D. L., editor, Kirtman, B., editor, Klopper, W., editor, Kutzelnigg, W., editor, March, N. H., editor, Mezey, P. G., editor, Müller, H., editor, Noga, J., editor, Paldus, J., editor, Pipek, J., editor, Raimondi, M., editor, Røeggen, I., editor, Sun, J. Q., editor, Surján, P. R., editor, Valdemoro, C., editor, and Vogtner, S., editor

Published
1999
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