Published August 7, 2023 | Version v1
Preprint Open

Data of the publication "Ab initio electron-lattice downfolding: potential energy landscapes, anharmonicity, and molecular dynamics in charge density wave materials"

  • 1. ROR icon Universität Hamburg
  • 2. University of Bremen
  • 3. ROR icon Lund University
  • 4. ROR icon Max Planck Institute for the Structure and Dynamics of Matter


This Zenodo repository has the purpose of providing data that was generated and/or used for the publication:
"Ab initio electron-lattice downfolding: potential energy landscapes, anharmonicity, and molecular dynamics in charge density wave materials"

This repository is a mixture of Python scripts, bash scripts and DFT (Quantum Espresso) data. 
To execute the Python scripts, the following packages need to be installed, which are saved in the file:

To install these requirements, use:
python3 -m pip install -r requirements.txt

With the following data one can reproduce Fig. 3:
The "" includes all Python scripts of model I,II and III. 

Using the bash script called "" should generate the free energy along direction of the 3x3 CDW
for 1H-TaS2 for all three models.

With the following data one can reproduce Fig. 4:
The .zip files of the materials "Carbon, TiSe2, NbS2 and TaS2" contain
- the input files for DFT (Quantum Espresso) for the unit cell and the CDW supercell
- the pseudopotentials
- the input files for the downfolded model III (generated by EPW calculations)

With the following data one can reproduce Fig. 7:
The "" contains the Python scripts and Quantum Espresso Input files to reproduce the benchmark.

With "", Fig. 7 can be reproduced immediately.

With the following data one can see an demonstrative example of Fig. 8 and 9:
The "" contains classical MD simulations up to 400ps. 
With the included Python scripts, it is possible to produce structure factor maps and an intensity plot along the temperature range.
Again, by using "", the data should be generated.


Abstract of the paper:
The interplay of electronic and nuclear degrees of freedom presents an outstanding problem in condensed matter physics and chemistry. Computational challenges arise especially for large systems, long time scales, in nonequilibrium, or in systems with strong correlations. In this work, we show how downfolding approaches facilitate complexity reduction on the electronic side and thereby boost the simulation of electronic properties and nuclear motion - in particular molecular dynamics (MD) simulations. Three different downfolding strategies based on constraining, unscreening, and combinations thereof are benchmarked against full density functional calculations for selected charge density wave (CDW) systems, namely 1H-TaS2, 1T-TiSe2, 1H-NbS2, and a one-dimensional carbon chain. We find that the downfolded models can reproduce potential energy surfaces on supercells accurately and facilitate computational speedup in MD simulations by about five orders of magnitude in comparison to purely ab initio calculations. For monolayer 1H-TaS2 we report classical replica exchange and quantum path integral MD simulations, revealing the impact of thermal and quantum fluctuations on the CDW transition.


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