An efficient method for hybrid density functional calculation with spin-orbit coupling

TL;DR

This paper introduces an efficient hybrid density functional calculation method with spin-orbit coupling that significantly reduces computational effort while maintaining accuracy, enabling practical calculations for complex materials.

Contribution

The paper develops a novel approximate method based on a mixed LCAO scheme to efficiently include SOC in hybrid functional calculations, which was previously computationally prohibitive.

Findings

Results closely match direct hybrid calculations with SOC

Computational effort is comparable to calculations without SOC

Method extends to magnetic materials

Abstract

In first-principles calculations, hybrid functional is often used to improve accuracy from local exchange correlation functionals. A drawback is that evaluating the hybrid functional needs significantly more computing effort. When spin-orbit coupling (SOC) is taken into account, the non-collinear spin structure increases computing effort by at least eight times. As a result, hybrid functional calculations with SOC are intractable in most cases. In this paper, we present an approximate solution to this problem by developing an efficient method based on a mixed linear combination of atomic orbital (LCAO) scheme. We demonstrate the power of this method using several examples and we show that the results compare very well with those of direct hybrid functional calculations with SOC, yet the method only requires a computing effort similar to that without SOC. The presented technique provides a good balance between computing efficiency and accuracy, and it can be extended to magnetic materials.