Ehrenfest dynamics with localized atomic-orbital basis sets within the projector augmented-wave method

TL;DR

This paper implements Ehrenfest molecular dynamics using localized atomic orbitals within the projector augmented-wave method, demonstrating its efficiency and accuracy for large systems and ion irradiation simulations.

Contribution

The authors introduce and validate an LCAO-based Ehrenfest dynamics implementation within GPAW, offering a computationally efficient alternative to real-space grid methods.

Findings

LCAO-ED achieves satisfactory accuracy at lower computational cost for modest velocities.

The method is effective for large systems and ion irradiation modeling.

Limitations and advantages compared to grid-based Ehrenfest dynamics are discussed.

Abstract

Density functional theory with linear combination of atomic orbitals (LCAO) basis sets is useful for studying large atomic systems, especially when it comes to computationally highly demanding time-dependent dynamics. We have implemented the Ehrenfest molecular dynamics (ED) method with the approximate approach of Tomfohr and Sankey within the projector augmented-wave code GPAW. We apply this method to small molecules as well as larger periodic systems, and elucidate its limits, advantages, and disadvantages in comparison to the existing implementation of Ehrenfest dynamics with a real-space grid representation. For modest atomic velocities, LCAO-ED shows satisfactory accuracy at a much reduced computational cost. This method will be particularly useful for modeling ion irradiation processes that require large amounts of vacuum in the simulation cell.