Vibrational Circular Dichroism from DFT Molecular Dynamics: The AWV Method

The paper illustrates the Activity Weighted Velocities (AWV) methodology to compute Vibrational Circular Dichroism (VCD) anharmonic spectra from Density Functional Theory (DFT) molecular dynamics. AWV calculates the spectra by the Fourier Transform of the time correlation functions of velocities, weighted by specific observables: the Atomic Polar Tensors (APTs) and the Atomic Axial Tensors (AATs). Indeed, AWV shows to correctly reproduce the experimental spectra for systems in the gas and liquid phases, both in the case of weakly and strongly interacting systems. The comparison with the experimental spectra is striking especially in the fingerprint region, as demonstrated by the three benchmark systems discussed: (1S)-Fenchone in the gas phase, (S)-(-)-Propylene oxide in the liquid phase, and (R)-(-)-2-butanol in the liquid phase. The time evolution of APTs and AATs can be adequately described by a linear combination of the tensors of a small set of appropriate reference structures, strongly reducing the computational cost without compromising accuracy. Additionally, AWV allows the partition of the spectral signal in its molecular components without any expensive postprocessing and any localization of the charge density or the wave function.

Automated summary

The paper presents the Activity Weighted Velocities (AWV) methodology for computing Vibrational Circular Dichroism (VCD) anharmonic spectra using Density Functional Theory (DFT) molecular dynamics. AWV accurately reproduces experimental spectra in both gas and liquid phase systems, particularly in the fingerprint region. By describing the time evolution of Atomic Polar Tensors (APTs) and Atomic Axial Tensors (AATs) through a linear combination of tensors from a small set of reference structures, computational cost is significantly reduced without sacrificing accuracy. AWV also allows partitioning of the spectral signal into its molecular components without the need for expensive postprocessing or charge density localization.