Perturbation-Adapted Perturbation Theory

• URL: http://arxiv.org/abs/2111.09271v3
• Date: Wed, 8 Dec 2021 07:39:48 GMT
• Title: Perturbation-Adapted Perturbation Theory
• Authors: Peter J. Knowles
• Abstract summary: It is constructed to be a best fit to the exact Hamiltonian within any desired functional form. strongly improved convergence is observed in cases where the conventional Fock hamiltonian leads to divergence or slow convergence.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: A new general approach is introduced for definining an optimum zero-order Hamiltonian for Rayleigh-Schr\"odinger perturbation theory. Instead of taking the operator directly from a model problem, it is constructed to be a best fit to the exact Hamiltonian within any desired functional form. When applied to many-body perturbation theory for electrons, strongly improved convergence is observed in cases where the conventional Fock hamiltonian leads to divergence or slow convergence.

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