Holomorphic Hartree–Fock Theory: An Inherently Multireference Approach

[Image] 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 H2 and H42+ and report the emergence of holomorphic solutions at points of symmetry breaking. Finally, we find these holomorphic solutions for H4 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.A.J.W.T. thanks the Royal Society for a University Research Fellowship (UF110161), and H.G.A.B. thanks the Royal Society of Chemistry for an Undergraduate Research Bursary.This is the author accepted manuscript. The final version is available from the American Chemical Society via http://dx.doi.org/10.1021/acs.jctc.5b0100