Theoretical description of time‐resolved pump/probe photoemission in TaS₂: a single‐band DFT+DMFT(NRG) study within the quasiequilibrium approximation

Abstract

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 (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)