Density Functional Computations of Vibrational Circular Dichroism Spectra beyond the Born-Oppenheimer Approximation

0524103 - ÚOCHB 2021 RIV US eng J - Článek v odborném periodiku
Tomeček, J. - Bouř, Petr
Density Functional Computations of Vibrational Circular Dichroism Spectra beyond the Born-Oppenheimer Approximation.
Journal of Chemical Theory and Computation. Roč. 16, č. 4 (2020), s. 2627-2634. ISSN 1549-9618. E-ISSN 1549-9626
Grant CEP: GA ČR(CZ) GA18-05770S; GA ČR(CZ) GA20-10144S
Institucionální podpora: RVO:61388963
Klíčová slova: vibronic coupling theory * transition-metal * 2nd derivatives
Obor OECD: Physical chemistry
Impakt faktor: 6.006, rok: 2020
Způsob publikování: Omezený přístup
https://pubs.acs.org/doi/10.1021/acs.jctc.0c00081

Transition-metal complexes provide rich features in vibrational circular dichroism (VCD) spectra, including significant intensity enhancements, and become thus useful in structural and functional studies of molecules. Quite often, however, the vibrational spectral bands are mixed with the electronic ones, and interpretation of such experiments is difficult. In the present study, we elaborate on the theory needed to calculate the VCD intensities beyond the Born-Oppenheimer (BO) approximation. Within a perturbation approach, the coupling between the electronic and vibrational states is estimated using the harmonic approximation and simplified wave functions obtainable from common density functional theory (DFT) computations. Explicit expressions, including Slater determinants and derivatives of molecular orbitals, are given. On a model diamine complex, the implementation is tested and factors affecting spectral intensities and frequencies are investigated. For two larger molecules, the results are in a qualitative agreement with previous experimental data. Typically, the electronic-vibrational interaction Hamiltonian coupling elements are rather small (similar to 0 to 10 cm(-1)), which provides negligible contributions to vibrational frequencies and absorption intensities. However, significant changes in VCD spectra are induced due to the large transition magnetic dipole moment associated with the d-d metal transitions. The possibility to model the spectra beyond the BO limit opens the way to further applications of chiral spectroscopy and transition-metal complexes.
Trvalý link: http://hdl.handle.net/11104/0308444