Harnessing dressed time-dependent density functional theory for the non-perturbative regime: Electron dynamics with double excitations

Abstract

Recent progress has been made in capturing spectral features of electronic states of double-excitation character in time-dependent density functional theory (TDDFT) through a frequency-dependent kernel. While it might appear that this development is limited to the perturbative regime, we show that when used within response-reformulated TDDFT, it accurately captures strong-field dynamics involving states of double-excitation character. More generally, this demonstrates how RR-TDDFT enables exchange-correlation functional developments in the response regime, which have so far been more successful than those in the non-linear regime, to be exploited for non-perturbative dynamics, thus significantly broadening their range of applications.

Figures (3)

• Figure 1: Rabi oscillations to the second excited state: a) Dipole predicted by the TDKS propagation with AEXX (green), AEXX used within RR-TDDFT (RR-AEXX, orange), DSMA/AEXX within RR-TDDFT (RR-DSMA, red), and exact (TDSE, black), each driven at their respective resonant frequency. The vertical lines indicate the half-Rabi period for the respective method, and the inset zooms into short times. b) The densities for each of the calculations in panel a, plotted at the respective $T_R/2$.
• Figure 2: The dipole moment driven with Pulse 1, predicted by a) TDKS propagation with AEXX (green, dashed), AEXX used within RR-TDDFT (RR-AEXX, orange), and exact (black), b) DSMA built on AEXX within RR-TDDFT (RR-DSMA, red), truncated TDCI (blue, dotted), and exact (black).
• Figure 3: The dipole moment driven by Pulse 2: a) predicted by TDKS propagation with AEXX (green, dashed), AEXX used within RR-TDDFT (RR-AEXX, orange), and exact (black), b) predicted by DSMA built on AEXX within RR-TDDFT (RR-DSMA, red), truncated TDCI (blue, dotted), and exact (black). c) Populations of the first 4 states under Pulse 2.