A favorably-scaling natural-orbital functional theory based on higher-order occupation probabilities
Abstract
We introduce a novel energy functional for ground-state electronic-structure calculations. Its fundamental variables are the natural spin-orbitals of the implied singlet many-body wave function and their joint occupation probabilities. The functional derives from a sequence of controlled approximations to the two-particle density matrix. Algebraic scaling of computational cost with electron number is obtainable in general, and Hartree-Fock scaling in the seniority-zero version of the theory. Results obtained with the latter version for saturated small molecular systems are compared with those of highly-accurate quantum-chemical computations. The numerical results are variational, capturing most of the correlation energy from equilibrium to dissociation. Their accuracy is considerably greater than that obtainable with current density-functional theory approximations and with current functionals of the one-particle density matrix only.
Keywords
Cite
@article{arxiv.1309.3929,
title = {A favorably-scaling natural-orbital functional theory based on higher-order occupation probabilities},
author = {Ralph Gebauer and Morrel H. Cohen and Roberto Car},
journal= {arXiv preprint arXiv:1309.3929},
year = {2015}
}