Correlation-Converged Virtual Orbitals for Accurate and Efficient Quantum Molecular Simulations

TL;DR

This paper introduces localized correlation-converged virtual orbitals (LCCVOs) to improve the accuracy and efficiency of quantum molecular simulations by better representing virtual orbitals in many-body Hamiltonians.

Contribution

The paper presents a novel LCCVO framework that reduces the number of orbitals needed while achieving high-accuracy dissociation energies in molecular systems.

Findings

LCCVOs yield dissociation energies comparable to high-level basis sets.

The approach demonstrates efficiency, scalability, and robustness.

LCCVOs improve virtual orbital descriptions in quantum chemical calculations.

Abstract

Density functional theory with plane-wave basis sets is widely employed in computational materials science, including applications to isolated molecular systems. However, the inadequate description of electron correlation remains a fundamental limitation. Accurate correlation treatments based on many-body Hamiltonians require reliable representations of both occupied and virtual orbitals, yet virtual orbitals are often poorly described in conventional computational schemes, resulting in reduced accuracy. In this work, we introduce localized correlation-converged virtual orbitals (LCCVOs) as an efficient basis for constructing accurate many-body Hamiltonians in molecular systems. Using a substantially reduced number of orbitals, the LCCVO framework yields dissociation energies for singlet, doublet, and triplet molecules that are comparable to, and in many cases exceed, those obtained with high-level correlation-consistent basis sets such as cc-pVXZ (X = D, T, Q, 5). These results demonstrate the efficiency, scalability, and robustness of the LCCVO approach for high-accuracy quantum chemical calculations.