Excited state calculations in solids by auxiliary-field quantum Monte Carlo

TL;DR

This paper introduces an auxiliary-field quantum Monte Carlo method with an orthogonalization constraint for accurate ab initio excited state calculations in solids, showing good agreement with experiments and GW results.

Contribution

The paper presents a novel approach for excited state calculations in solids using AFQMC with an orthogonalization constraint, improving accuracy and stability.

Findings

Accurate band structures for standard semiconductors

Fundamental band gap of ZnO wurtzite structure: 3.26 eV

Good agreement with GW and experimental data

Abstract

We present an approach for ab initio many-body calculations of excited states in solids. Using auxiliary-field quantum Monte Carlo, we introduce an orthogonalization constraint to prevent collapse of the stochastic Slater determinants in the imaginary-time propagation. Trial wave functions from density-functional calculations are used for the constraints. Detailed band structures calculated for standard semiconductors are in good agreement with GW and experimental results. For the challenging ZnO wurtzite structure, we obtain a fundamental band gap of 3.26(16) eV, consistent with experiments.