Theoretical description of time-resolved pump/probe photoemission in TaS\_2: a single-band DFT+DMFT(NRG) study within the quasiequilibrium approximation

TL;DR

This study provides a theoretical analysis of time-resolved pump/probe photoemission in TaS extsubscript{2} using DFT+DMFT(NRG), revealing insights into its electronic structure and limitations of the quasiequilibrium approximation.

Contribution

It introduces a comprehensive theoretical framework combining DFT and DMFT(NRG) for analyzing pump/probe photoemission in strongly correlated materials like TaS extsubscript{2}.

Findings

Bare band structure shows more dispersion perpendicular to planes.

DMFT reproduces Hubbard bands similar to experiments.

Finite probe pulse width minimally affects spectra.

Abstract

In this work, we theoretically examine recent pump/probe photoemission experiments on the strongly correlated charge-density-wave insulator TaS\_2. We describe the general nonequilibrium many-body formulation of time-resolved photoemission in the sudden approximation, and then solve the problem using dynamical mean-field theory with the numerical renormalization group and a bare density of states calculated from density functional theory including the charge-density-wave distortion of the ion cores and spin-orbit coupling We find a number of interesting results: (i) the bare band structure actually has more dispersion in the perpendicular direction than in the two-dimensional planes; (ii) the DMFT approach can produce upper and lower Hubbard bands that resemble those in the experiment, but the upper bands will overlap in energy with other higher energy bands; (iii) the effect of the finite width of the probe pulse is minimal on the shape of the photoemission spectra; and (iv) the quasiequilibrium approximation does not fully describe the behavior in this system.