A Transcorrelated Wave-Function Framework for Solids: An Application to Bulk and Defected Silicon

TL;DR

This paper introduces a transcorrelated wave-function framework for solids, improving basis convergence and defect energy calculations in silicon by integrating periodic TC theory with fragment-based solvers.

Contribution

It extends transcorrelated methods to periodic systems and develops an embedding framework that enhances wave-function accuracy for solids and defects.

Findings

Rapid basis convergence in silicon calculations

Accurate defect formation energies at triple-zeta level

Reduced basis-set bottleneck for crystalline defects

Abstract

Accurate wave-function descriptions of pristine and defected solids remain challenging due to the simultaneous presence of finite-size, basis-set, and correlation errors. While embedding techniques alleviate finite-size effects and correlated wave-function approaches systematically improve correlation, basis-set incompleteness continues to limit practical accuracy. Here we present a study of transcorrelated (TC) many-body wave-function methods on properties of solid state systems. We augment the existing xTC theory to periodic systems, and establish an unified transcorrelated embedding framework that integrates periodic TC theory with fragment-based correlated solvers. Using silicon as a test case, we validate the method against coupled-cluster, FCIQMC, and diffusion Monte Carlo benchmarks for bulk. Then we apply TC embedding to calculation of formation energies of two silicon self-interstitials. The TC Hamiltonian yields rapid basis convergence and quantitatively reliable defect formation energies at the triple-$\zeta$ level, substantially reducing the basis-set bottleneck for wave-function treatments of crystalline defects.