Transverse spin gradient functional for non-collinear spin density functional theory

TL;DR

This paper introduces a new spin density functional that accounts for non-collinear magnetic structures by incorporating transverse spin gradients, enabling more accurate modeling of complex magnetic states.

Contribution

The paper develops a novel functional based on the spin-spiral-wave state, sensitive to local spin direction changes, and demonstrates its application to a non-collinear chromium monolayer.

Findings

Functional depends on transverse spin gradients.

Exchange-correlation magnetic field is non-parallel to spin magnetization.

Successfully applied to non-collinear chromium monolayer.

Abstract

We present a novel functional for spin density functional theory aiming at the description of non-collinear magnetic structures. The construction of the functional employs the spin-spiral-wave state of the uniform electron gas as reference system. We show that the functional depends on transverse gradients of the spin magnetization, i.e., in contrast to the widely used local spin density approximation, the functional is sensitive to local changes of the direction of the spin magnetization. As a consequence the exchange-correlation magnetic field is not parallel to the spin magnetization and a local spin-torque is present in the ground state of the Kohn-Sham system. As a proof-of-principle we apply the functional to a Chromium mono-layer in the non-collinear ${120^{\circ}}$-N{\'e}el state.