Accurate and efficient treatment of spin-orbit coupling via second variation employing local orbitals

• Main Authors: Vona, Cecilia, Lubeck, Sven, Kleine, Hannah, Gulans, Andris, Draxl, Claudia
• Format: Journal Article
• Language: English
• Published: 05-06-2023
• Subjects: Physics - Materials Science
• DOI: 10.48550/arxiv.2306.02965

A new method is presented that allows for efficient evaluation of spin-orbit
coupling (SOC) in density-functional theory calculations. In the so-called
second-variational scheme, where Kohn-Sham functions obtained in a
scalar-relativistic calculation are employed as a new basis for the
spin-orbit-coupled problem, we introduce a rich set of local orbitals as
additional basis functions. Also relativistic local orbitals can be used. The
method is implemented in the all-electron full-potential code \exciting. We
show that, for materials with strong SOC effects, this approach can reduce the
overall basis-set size and thus computational costs tremendously.