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OO-REMP: Approaching Chemical Accuracy with Second-Order Perturbation Theory
Stefan Behnle1, Reinhold F Fink1
1Eberhard Karls Universität, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Abstract:
We present a perturbation theory (PT) providing second-order energies that reproduce main group chemistry benchmark sets for reaction energies, barrier heights, and atomization energies with mean absolute deviations below 1 kcal mol-1. The PT is defined as a constrained mixture of the unperturbed Hamiltonians of the Retaining the Excitation degree (RE) and the Møller-Plesset (MP) PTs. The orbitals of the reference wave function, a single unrestricted Slater determinant, are iteratively optimized to minimize the total energy. For all benchmark sets, good and near optimal performance of OO-REMP was observed for an unperturbed Hamiltonian consisting of 25% MP and 75% RE contributions.
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