Spin-spin interactions in solids from mixed all-electron and pseudopotential calculations $-$ a path to screening materials for spin qubits

TL;DR

This paper introduces a real-space density functional theory approach combining all-electron and pseudopotential methods to accurately compute spin-spin interactions in large solid-state systems, aiding the screening of materials for spin qubits.

Contribution

The authors develop a scalable hybrid all-electron/pseudopotential method for calculating spin-Hamiltonian parameters in large solids, enabling accurate modeling of spin defects.

Findings

Accurate hyperfine and zero-field splitting tensors can be obtained with minimal all-electron treatment.

The method is demonstrated on defects in diamond and silicon carbide with over 1000 atoms.

Results show the importance of precise parameters for predicting spin coherence times.

Abstract

Understanding the quantum dynamics of spin defects and their coherence properties requires accurate modeling of spin-spin interaction in solids and molecules, for example by using spin Hamiltonians with parameters obtained from first-principles calculations. We present a real-space approach based on density functional theory for the calculation of spin-Hamiltonian parameters, where only selected atoms are treated at the all-electron level, while the rest of the system is described with the pseudopotential approximation. Our approach permits calculations for systems containing more than 1000 atoms, as demonstrated for defects in diamond and silicon carbide. We show that only a small number of atoms surrounding the defect needs to be treated at the all-electron level, in order to obtain an overall all-electron accuracy for hyperfine and zero-field splitting tensors. We also present results for coherence times, computed with the cluster correlation expansion method, highlighting the importance of accurate spin-Hamiltonian parameters for quantitative predictions of spin dynamics.