Prediction of many-electron wavefunctions using atomic potentials: extended basis sets and molecular dissociation

TL;DR

This paper introduces a method using special atomic potentials to accurately predict many-electron wavefunctions and energies in molecules, extending previous work to larger basis sets and dissociation processes, with results closely matching traditional CI calculations.

Contribution

The work develops a one-electron potential approach that produces accurate molecular orbitals for diverse bonding situations without modification, extending previous methods to larger basis sets and dissociation.

Findings

Wavefunction energies deviate less than 0.04 eV per bond from CI energies.

Errors are reduced to 0.01 eV with a single Fock matrix diagonalization.

Dissociation energy curves closely match CI results across all internuclear distances.

Abstract

A one-electron Schroedinger equation based on special one-electron potentials for atoms is shown to exist that produces orbitals for an arbitrary molecule that are sufficiently accurate to be used without modification to construct single- and multi-determinant wavefunctions. The exact Hamiltonian is used to calculate the energy variationally and to generate configuration interaction expansions. Earlier work on equilibrium geometries is extended to larger basis sets and molecular dissociation. For a test set of molecules representing different bonding environments, a single set of invariant atomic potentials gives wavefunctions with energies that deviate from configuration interaction energies based on SCF orbitals by less than 0.04 eV per bond or valence electron pair. On a single diagonalization of the Fock matrix, the corresponding errors are reduced 0.01 eV. Atomization energies are also in good agreement with CI values based on canonical SCF orbitals. Configuration interaction applications to single bond dissociations of water and glycine, and multiple bond dissociations of ethylene and oxygen produce dissociation energy curves in close agreement with CI calculations based on canonical SCF orbitals for the entire range of internuclear distances.