Optimized Non-Orthogonal Localized Orbitals for Electronic Structure Calculations: Improved Linear Scaling Quantum Monte Carlo

TL;DR

This paper introduces a method to generate highly localized, non-orthogonal orbitals that significantly enhance the efficiency of linear scaling quantum Monte Carlo calculations for both semiconductors and metals.

Contribution

The authors develop an automatic procedure for creating localized, non-orthogonal orbitals, improving computational efficiency and enabling linear scaling QMC for metallic systems.

Findings

Reduced computational time by a factor of five for silicon

Decreased memory usage by a factor of six for silicon

Achieved energy convergence in metallic systems with localized orbitals

Abstract

We derive an automatic procedure for generating a set of highly localized, non-orthogonal orbitals for linear scaling quantum Monte Carlo calculations. We demonstrate the advantage of these orbitals in calculations of the total energy of both semiconducting and metallic systems by studying bulk silicon and the homogeneous electron gas. For silicon, the improved localization of these orbitals reduces the computational time by a factor five and the memory by a factor of six compared to localized, orthogonal orbitals. For jellium, we demonstrate that the total energy is converged for orbitals truncated within spheres with radii 7-8 $r_s$, opening the possibility of linear scaling QMC calculations for realistic metallic systems.