Nuclear velocity perturbation theory for vibrational circular dichroism: An approach based on the exact factorization of the electron-nuclear wave function

Arne Scherrer; Federica Agostini; Daniel Sebastiani; E K U Gross; Rodolphe Vuilleumier

doi:10.1063/1.4928578

Nuclear velocity perturbation theory for vibrational circular dichroism: An approach based on the exact factorization of the electron-nuclear wave function

J Chem Phys. 2015 Aug 21;143(7):074106. doi: 10.1063/1.4928578.

Authors

Arne Scherrer¹, Federica Agostini², Daniel Sebastiani¹, E K U Gross², Rodolphe Vuilleumier³

Affiliations

¹ Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle, Germany.
² Max-Planck-Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany.
³ UMR 8640 ENS-CNRS-UPMC, Département de Chimie, 24 rue Lhomond, École Normale Supérieure, 75005 Paris, France.

PMID: 26298114
DOI: 10.1063/1.4928578

Abstract

The nuclear velocity perturbation theory (NVPT) for vibrational circular dichroism (VCD) is derived from the exact factorization of the electron-nuclear wave function. This new formalism offers an exact starting point to include correction terms to the Born-Oppenheimer (BO) form of the molecular wave function, similar to the complete-adiabatic approximation. The corrections depend on a small parameter that, in a classical treatment of the nuclei, is identified as the nuclear velocity. Apart from proposing a rigorous basis for the NVPT, we show that the rotational strengths, related to the intensity of the VCD signal, contain a new contribution beyond-BO that can be evaluated with the NVPT and that only arises when the exact factorization approach is employed. Numerical results are presented for chiral and non-chiral systems to test the validity of the approach.