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arXiv · 1404.1426

Projected seniority-two orbital optimization of the Antisymmetric Product of one-reference orbital Geminal

Katharina Boguslawski·Paweł Tecmer·Peter A. Limacher·Paul A. Johnson·Paul W. Ayers·Patrick Bultinck·Stijn De Baerdemacker·Dimitri Van Neck
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Abstract

We present a new, non-variational orbital-optimization scheme for the Antisymmetric Product of one-reference orbital Geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [J. Chem. Phys., 135, 044119 (2011)]. A numerical analysis is performed for the C$_2$, LiF and CH$_2$ molecules as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.

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Katharina Boguslawski, Paweł Tecmer, Peter A. Limacher, Paul A. Johnson, Paul W. Ayers, Patrick Bultinck, Stijn De Baerdemacker, Dimitri Van Neck. 2014-04-11. Projected seniority-two orbital optimization of the Antisymmetric Product of one-reference orbital Geminal. https://doi.org/10.1063/1.4880820

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