Explicitly correlated quantum chemical calculations require calculations of five types of two-electron integrals beyond the standard electron repulsion integrals. We present a novel scheme, which utilises general ideas of the McMurchie-Davidson technique, to compute these integrals when the so-called “range-separated” correlation factor is used. This correlation factor combines the well-known short range behaviour resulting from the electronic cusp condition, with the exact long-range asymptotics derived for the helium atom [Lesiuk, Jeziorski, and Moszynski, J. Chem. Phys. 139, 134102 (2013)]. Almost all steps of the presented procedure are formulated recursively, so that an efficient implementation and control of the precision are possible. Additionally, the present formulation is very flexible and general, and it allows for use of an arbitrary correlation factor in the electronic structure calculations with minor or no changes.
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Research Article| March 23 2015
Calculation of the molecular integrals with the range-separated correlation factor
Michał Silkowski, Michał Lesiuk, Robert Moszynski; Calculation of the molecular integrals with the range-separated correlation factor. J. Chem. Phys. 28 March 2015; 142 (12): 124102. https://doi.org/10.1063/1.4915272
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