Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 48: Poster Surface Dynamics
O 48.4: Poster
Tuesday, March 18, 2025, 18:00–20:00, P2
Predicting and modelling incommensurate charge density waves in 1H-TaSe2 via downfolding approach — •Clara Pfister1,2, Laura Pätzold1, and Tim O. Wehling1,2 — 1I. Institute of Theoretical Physics, U Hamburg — 2The Hamburg Centre for Ultrafast Imaging, Hamburg
Studying the emergence and thermodynamic behaviour of symmetry-broken phases such as charge density waves (CDWs) in solids is of great interest to deepen our understanding of collective phenomena and interactions between electrons and the crystal lattice. Incommensurate CDWs (ICCDWs) are especially intriguing because a realistic and efficient computational method to predict them has not been developed yet. To model ICCDW phases in the exemplary transition metal dichalcogenide material 1H-TaSe2, we employed a downfolding approach that reduces the electronic degrees of freedom by retaining only the low-energy subspace relevant to CDW formation. This method achieves a computational speed-up of approximately five orders of magnitude compared to purely ab initio calculations [1], making it possible to simulate sufficiently large supercells efficiently. Our approach allows for modelling the ICCDW with reasonable accuracy, with the predicted temperature range for its occurrence agreeing well with experimental results of the ICCDW in undoped 2H-TaSe2 [2]. This suggests that our approach is applicable for the description of other materials exhibiting ICCDWs.
[1] A. Schobert et al., SciPost Phys. 16, 046 (2024)
[2] X. Shen et al., Nat. Commun. 14, 7282 (2023)
Keywords: TaSe2; Molecular Dynamics; Downfolding; Charge Density Waves; Phase Transitions