Nonadiabatic Molecular Dynamics for Thousand Atom Systems: A Tight-Binding Approach toward PYXAID

Area of Science:

• Computational Chemistry and Materials Science
• Quantum Nanodynamics

Background:

• Simulating excited state dynamics in nanoscale systems with many atoms is computationally demanding.
• Electronic structure calculations often represent the primary computational bottleneck.
• Accurate modeling is crucial for understanding phenomena like electron-hole relaxation and recombination.

Purpose of the Study:

• To develop an efficient computational approach for nonadiabatic molecular dynamics (NA-MD) of large nanoscale systems.
• To enable accurate simulation of excited state processes in realistic materials.
• To reduce the computational cost associated with nanoscale dynamics simulations.

Main Methods:

• Combined self-consistent charge density functional tight binding (SCC-DFTB) with fewest switches surface hopping (FSSH) and decoherence induced surface hopping (DISH) techniques.
• Implemented the approach within the open-source Python extension for ab initio dynamics (PYXAID) package.
• Validated the method against ab initio DFT calculations and experimental data.

Main Results:

• Successfully simulated intraband electron and hole relaxation in a CdSe quantum dot.
• Accurately modeled nonradiative electron-hole recombination in a (10,5) semiconducting carbon nanotube.
• Demonstrated efficient and accurate treatment of excitation dynamics in large nanoscale materials.

Conclusions:

• The developed SCC-DFTB-based NA-MD approach offers an efficient and accurate method for studying excited state dynamics in complex nanoscale materials.
• This technique significantly reduces computational resource requirements.
• The PYXAID implementation provides a versatile tool for nanoscale materials simulation.