A general framework for active space embedding methods: applications in quantum computing

TL;DR

This paper introduces a versatile hybrid quantum-classical framework for embedding methods in molecular and periodic systems, demonstrated through applications in material electronic states and optical property predictions.

Contribution

It presents a novel general framework for active space embedding in quantum computing, integrating periodic DFT with quantum algorithms for improved material simulations.

Findings

Accurately predicts optical properties of MgO vacancy

Shows competitive performance with ab initio methods

Excellent agreement with experimental photoluminescence data

Abstract

We developed a general framework for hybrid quantum-classical computing of molecular and periodic embedding approaches based on an orbital space separation of the fragment and environment degrees of freedom. We demonstrate its potential by presenting a specific implementation of periodic range-separated DFT coupled to a quantum circuit ansatz, whereby the variational quantum eigensolver and the quantum equation-of-motion algorithm are used to obtain the low-lying spectrum of the embedded fragment Hamiltonian. Application of this scheme to study localized electronic states in materials is showcased through the accurate prediction of the optical properties of the neutral oxygen vacancy in magnesium oxide (MgO). Despite some discrepancies in the position of the main absorption band, the method demonstrates competitive performance compared to state-of-the-art ab initio approaches, particularly evidenced by the excellent agreement with the experimental photoluminescence emission peak.