Systematic study of finite-size effects in quantum Monte Carlo calculations of real metallic systems

TL;DR

This paper systematically analyzes finite-size effects in quantum Monte Carlo calculations of metals, comparing correction schemes and introducing practical improvements, with results for lithium and aluminum showing high accuracy.

Contribution

It provides a comprehensive comparison of finite-size correction methods and introduces an efficient correction scheme combining twist averaging and DFT.

Findings

All correction methods tested show excellent agreement for lithium and aluminum.

The proposed correction scheme improves accuracy and efficiency.

Finite-size effects can be effectively mitigated with the methods studied.

Abstract

We present a systematic and comprehensive study of finite-size effects in diffusion quantum Monte Carlo calculations of metals. Several previously introduced schemes for correcting finite-size errors are compared for accuracy and efficiency and practical improvements are introduced. In particular, we test a simple but efficient method of finite-size correction based on an accurate combination of twist averaging and density functional theory. Our diffusion quantum Monte Carlo results for lithium and aluminum, as examples of metallic systems, demonstrate excellent agreement between all of the approaches considered.