Improving the accuracy and efficiency of time-resolved electronic spectra calculations: Cellular dephasing representation with a prefactor

TL;DR

This paper enhances the dephasing representation method for calculating time-resolved electronic spectra by improving its accuracy with a phase-space propagator correction and its efficiency with a cellular scheme, demonstrated on various molecular systems.

Contribution

It introduces a combined amplitude correction and cellular scheme to improve the accuracy and efficiency of time-resolved spectra calculations using the dephasing representation.

Findings

Improved accuracy with phase-space propagator correction.

Enhanced efficiency through inverse Weierstrass transform and optimal cell scaling.

Different methods perform better depending on system chaos level.

Abstract

Time-resolved electronic spectra can be obtained as the Fourier transform of a special type of time correlation function known as fidelity amplitude, which, in turn, can be evaluated approximately and efficiently with the dephasing representation. Here we improve both the accuracy of this approximation---with an amplitude correction derived from the phase-space propagator---and its efficiency---with an improved cellular scheme employing inverse Weierstrass transform and optimal scaling of the cell size. We demonstrate the advantages of the new methodology by computing dispersed time-resolved stimulated emission spectra in the harmonic potential, pyrazine, and the NCO molecule. In contrast, we show that in strongly chaotic systems such as the quartic oscillator the original dephasing representation is more appropriate than either the cellular or prefactor-corrected methods.