Scherrer, A., Agostini, F., Sebastiani, D., Gross, E. K. U., Vuilleumier, R.
Nuclear velocity perturbation theory for vibrational circular dichroism:
An approach based on the exact factorization of the electron-nuclear
wave function
Journal of Chemical Physics 143, (7),pp 074106/1-12 (2015)
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.
TH-2015-29