We present a new velocity-gauge real-time, time-dependent density functional tight-binding (VG-rtTDDFTB) implementation in the open-source DFTB+ software package (https://dftbplus.org) for probing electronic excitations in large, condensed matter systems. Our VG-rtTDDFTB approach enables real-time electron dynamics simulations of large, periodic, condensed matter systems containing thousands of atoms with a favorable computational scaling as a function of system size. We provide computational details and benchmark calculations to demonstrate its accuracy and computational parallelizability on a variety of large material systems. As a representative example, we calculate laser-induced electron dynamics in a 512-atom amorphous silicon supercell to highlight the large periodic systems that can be examined with our implementation. Taken together, our VG-rtTDDFTB approach enables new electron dynamics simulations of complex systems that require large periodic supercells, such as crystal defects, complex surfaces, nanowires, and amorphous materials.
@article{arxiv.2308.09782,
title = {Velocity-gauge real-time time-dependent density functional tight-binding for large-scale condensed matter systems},
author = {Qiang Xu and Mauro Del Ben and Mahmut Sait Okyay and Min Choi and Khaled Z. Ibrahim and Bryan M. Wong},
journal= {arXiv preprint arXiv:2308.09782},
year = {2024}
}