Erratum: Ultrafast Doublon Dynamics in Photoexcited 1T−TaS2 [Phys. Rev. Lett. 120 , 166401 (2018)]

Surface structure and stacking of the commensurate (13×13)R13.9∘ charge density wave phase of

“…First, it is a remarkable finding that a vertically on-top-stacked doubletrilayer is pinned at the surface as this structural unit has been identified as the driver of CDW stacking-induced energy-gap formation at the Fermi level [14,19,21]. Regarding the question about the nature of the ground state of bulk 1T -TaS 2 , which density functional theory calculations predicts to be a Peierls-type insulator [18,19,21], whereas (surface-sensitive) time-and angle-resolved photoemission spectroscopy results indicate dominance of local Mott physics [9][10][11][12], this appears to favor the former interpretation. However, it is also possible that the atomic surface structure reported here gives rise to a surface Mott phase.…”

“…The 1T polytype with octahedrally coordinated Ta atoms exhibits one commensurate ( √ 13 × √ 13)R13.9 • chargedensity wave phase (C-phase, T < 187 K) and other non-commensurate CDW states at higher temperatures (187 K -543 K) [1]. Having been known for decades, these different phases and their transitions [2] are experiencing renewed and growing interest, e.g., following the discovery of pressure-induced superconductivity [3] and optical and electrical switching to metastable "hidden" CDW states [4][5][6][7][8], the observation of ultrafast electronic structure changes at the surface [9][10][11][12] and trilayer number-dependent CDW phases in thin crystals [13], as well as the prediction of complex orbital textures [14] and a quantum spin-liquid state associated with the Cphase [15,16]. Whereas the electronic properties of a single trilayer may often be a good starting point to ex- * lutz.hammer@fau.de plain these various phenomena [17], it has recently become clear that a full understanding of the electronic structure of the CDW states requires to include interlayer coupling and the stacking order of the CDW perpendicular to the trilayers [14].…”

“…In the C-phase of 1T -TaS 2 , for example, different CDW stackings can result in metallic or insulating behavior within the trilayers, but also in a state that corresponds to a band insulator within the trilayers and a metal in the perpendicular direction [18][19][20][21]. Thus, detailed knowledge of the three-dimensional atomic and electronic CDW structure is essential, and particularly its modification at the surface as many of the recent key experimental observations were made by surface-sensitive techniques such as scanning tunneling microscopy [5,7,8], time-and angle-resolved photoemission spectroscopy [9][10][11][12], or ultrafast LEED [2].…”

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019)

“…In such experiments a probe is excited and the subsequent relaxation is studied. One example is the ultrafast dynamics of doubly occupied sites in the photo-excited quasi-2d transition-metal dichalcogenide 1T-TaS 2 [89]. Such excitations may even result in long-lived, metastable ("hidden") states [90].…”

Low rank compression in the numerical solution of the nonequilibrium Dyson equation

“…The numerical solution of the quantum many-body problem out of equilibrium is an outstanding challenge in modern physics, required to simulate the effect of strong radiation fields on atoms and molecules [1,2], quantum materials [3][4][5], nuclear physics [6][7][8], ultracold atomic gases [9][10][11], and many other systems. Various theoretical frameworks for equilibrium problems have been extended to the nonequilibrium situation, including density functional theory [12], the density matrix renormalization group (DMRG) [13], and field theory approaches based on the Keldysh formalism [14][15][16][17].…”