iOI: an Iterative Orbital Interaction Approach for Solving the Self-Consistent Field Problem

TL;DR

The paper introduces iOI, a novel iterative orbital interaction method that efficiently solves the self-consistent field problem by adaptively merging subsystems to accurately determine wave functions in quantum chemistry.

Contribution

It presents a new bottom-up, fragment-based approach that divides and conquers both energy and wave functions, with automatic subsystem size determination.

Findings

Successfully merges neighboring subsystems for convergence

Produces orthonormal localized molecular orbitals

Applicable for post-SCF quantum chemistry tasks

Abstract

An iterative orbital interaction (iOI) approach is proposed to solve, in a bottom-up fashion, the self-consistent field problem in quantum chemistry. While it belongs grossly to the family of fragment-based quantum chemical methods, iOI is distinctive in that (1) it divides and conquers not only the energy but also the wave function, and that (2) the subsystems sizes are automatically determined by successively merging neighboring small subsystems until they are just enough for converging the wave function to a given accuracy. Orthonormal occupied and virtual localized molecular orbitals are obtained in a natural manner, which can be used for all post-SCF purposes.