Holomorphic Hartree-Fock theory: an inherently multireference approach

TL;DR

This paper introduces holomorphic Hartree-Fock theory as a multireference approach, demonstrating its ability to find solutions at symmetry-breaking points and accurately approximate full configuration interaction energies.

Contribution

It presents a revised SCF algorithm to identify holomorphic solutions and applies these solutions to H2, H4^{2+}, and H4, showing their effectiveness in energy calculations.

Findings

Holomorphic solutions emerge at symmetry-breaking points.

Holomorphic solutions enable accurate energy approximations.

The approach aligns well with full configuration interaction results.

Abstract

We investigate the existence of holomorphic Hartree-Fock solutions using a revised SCF algorithm. We use this algorithm to study the Hartree-Fock solutions for H$_{2}$ and H$_{4}^{2+}$ and report the emergence of holomorphic solutions at points of symmetry breaking. Finally, we find these holomorphic solutions for H$_{4}$ and use them as a basis for Non-Orthogonal Configuration Interaction at a range of rectangular geometries and show them to produce energies in good agreement with Full Configuration Interaction.