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Second-order Møller–Plesset perturbation theory with terms linear in the interelectronic coordinates and exact evaluation of three-electron integrals |
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| Authors: | Peter Wind Wim Klopper Trygve Helgaker |
| Institution: | Institute of Chemistry, University of Troms?, 9037 Troms?, Norway, NO Theoretical Chemistry Group, Debye Institute, Utrecht University, P.O. Box 80052, 3508 TB Utrecht, The Netherlands, NL Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway, NO |
| Abstract: | The second-order correlation energy of M?ller–Plesset perturbation theory is computed for the neon atom using a wave function that depends explicitly on the interelectronic coordinates (MP2-R12). The resolution-of-identity (RI) approximation, which is invoked in the standard formulation of MP2-R12 theory, is largely avoided by rigorously computing the necessary three-electron integrals. The basis-set limit for the second-order correlation energy is reached to within 0.1 mE h. A comparison with the conventional RI-based MP2-R12 method shows that only three-electron integrals over s and p orbitals need to be computed exactly, indicating that the RI approximation can be safely used for integrals involving orbitals of higher angular momentum. Received: 9 May 2001 / Accepted: 31 October 2001 / Published online: 9 January 2002 |
| Keywords: | : Neon atom – Second-order energy – Interelectronic coordinates – Three-electron integrals – Strong orthogonality |
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