Dynamical analysis of attosecond molecular modes

Abstract

Attosecond charge migration (CM) modes in halogenated hydrocarbon chains are investigated from first principles. The initial hole state on the Br site is created by the constrained density functional theory (CDFT) and the following CM dynamics is tracked by the time-dependent density functional theory (TDDFT). We find the attosecond mode is mainly recorded in the spin channel where the electron is initially ionized. By employing approximate functionals at different theory levels, we find the local density approximation gives satisfactory results to reproduce the attosecond mode and more advanced exchange-correlation functionals do not affect the mode significantly. By alleviating the self-interaction error with an average density correction or allowing nuclei to relax, it is shown that the nuclear motion is a key factor to alter the mode. In addition, by a detailed analysis of single-electron orbitals, we find the attosecond mode is attributed to the electronic collective motion in the outermost energy shell. Our results will be useful in understanding the mechanism of molecular modes and motivating the ultrafast CM detection methods for future experiments.