Charge self-consistent many-body corrections using optimized projected localized orbitals

TL;DR

This paper introduces a flexible and efficient charge self-consistent implementation of many-body corrections using optimized localized orbitals within VASP, improving accuracy in correlated materials simulations.

Contribution

It presents a novel implementation of charge self-consistent many-body corrections with optimized projectors in VASP, enhancing the reliability and efficiency of ab initio + many-body methods.

Findings

Charge self-consistency reduces spectral function dependence on double counting.

Optimized projectors improve the accuracy of many-body calculations.

Electronic correlations influence structural parameters like oxygen positions.

Abstract

In order for methods combining ab initio density-functional theory and many-body techniques to become routinely used, a flexible, fast, and easy-to-use implementation is crucial. We present an implementation of a general charge self-consistent scheme based on projected localized orbitals in the projector augmented wave framework in the Vienna Ab Initio Simulation Package (VASP). We give a detailed description on how the projectors are optimally chosen and how the total energy is calculated. We benchmark our implementation in combination with dynamical mean-field theory: first we study the charge-transfer insulator NiO using a Hartree-Fock approach to solve the many-body Hamiltonian. We address the advantages of the optimized against non-optimized projectors and furthermore find that charge self-consistency decreases the dependence of the spectral function - especially the gap - on the double counting. Second, using continuous-time quantum Monte Carlo we study a monolayer of SrVO$_3$, where strong orbital polarization occurs due to the reduced dimensionality. Using total-energy calculation for structure determination, we find that electronic correlations have a non-negligible influence on the position of the apical oxygens, and therefore on the thickness of the single SrVO$_3$ layer.