Velocity-Gauge Real-Time Time-Dependent Density Functional Tight-Binding for Large-Scale Condensed Matter Systems

Area of Science:

• Computational Physics
• Materials Science
• Quantum Chemistry

Background:

• Accurate simulation of electronic excitations in large condensed matter systems is computationally demanding.
• Existing methods often struggle with the scale and complexity of real-world materials.

Purpose of the Study:

• To introduce a new, computationally efficient method for real-time electron dynamics simulations.
• To enable the study of electronic excitations in large, periodic condensed matter systems.

Main Methods:

• Implementation of a velocity-gauge real-time, time-dependent density functional tight-binding (VG-rtTDDFTB) approach.
• Utilizing the open-source DFTB+ software package for simulations.
• Benchmarking accuracy and parallelizability on various large material systems.

Main Results:

• The VG-rtTDDFTB method demonstrates favorable computational scaling for systems with thousands of atoms.
• Successful simulation of laser-induced electron dynamics in a 512-atom amorphous silicon supercell.
• Validation of accuracy and computational parallelizability across diverse material types.

Conclusions:

• The VG-rtTDDFTB approach significantly advances the simulation capabilities for large, complex condensed matter systems.
• This method opens new avenues for studying electron dynamics in systems like crystal defects, surfaces, nanowires, and amorphous materials.