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- Title
Explicitly correlated RMP2 for high-spin open-shell reference states.
- Authors
Knizia, Gerald; Werner, Hans-Joachim
- Abstract
We present an explicitly correlated version of the high-spin open-shell RMP2 method. The theory is derived in a unitarily invariant form, which is suitable for the insertion of local approximations. It is demonstrated that the rapid basis set convergence of closed-shell MP2-F12 is also achieved in RMP2-F12, and similar Ansatze and approximations can be employed. All integrals are computed using efficient density fitting approximations, and many-electron integrals are avoided using resolution of the identity approximations. The performance of the method is demonstrated by benchmark calculations on a large set of ionization potentials, electron affinities and atomization energies. Using triple-zeta basis sets RMP2-F12 yields results that are closer to the basis set limit than standard RMP2 with augmented quintuple-zeta basis sets for all properties. Different variants of perturbative corrections for the open-shell Hartree-Fock treatment are described and tested.
- Publication
The Journal of chemical physics, 2008, Vol 128, Issue 15, p154103
- ISSN
0021-9606
- Publication type
Journal Article
- DOI
10.1063/1.2889388