Lattice Dynamics Calculations based on Density-functional Perturbation Theory in Real Space

TL;DR

This paper develops a real-space formalism for density-functional perturbation theory to compute vibrational properties efficiently in molecules and solids, demonstrating its implementation and scalability in the FHI-aims package.

Contribution

It introduces a novel real-space approach for DFPT and implements it with numeric atom-centered orbitals, enabling efficient vibrational calculations.

Findings

Convergence behavior is thoroughly analyzed.

Comparison with finite-difference methods shows good agreement.

Scalability tests confirm high computational efficiency.

Abstract

A real-space formalism for density-functional perturbation theory (DFPT) is derived and applied for the computation of harmonic vibrational properties in molecules and solids. The practical implementation using numeric atom-centered orbitals as basis functions is demonstrated exemplarily for the all-electron Fritz Haber Institute ab initio molecular simulations (FHI-aims) package. The convergence of the calculations with respect to numerical parameters is carefully investigated and a systematic comparison with finite-difference approaches is performed both for finite (molecules) and extended (periodic) systems. Finally, the scaling tests and scalability tests on massively parallel computer systems demonstrate the computational efficiency.