Analytical energy gradients for local second-order Moller-Plesset perturbation theory
by El Azhary, A.; Rauhut, G.; Pulay, P.; Werner, H. J.
Based on the orbital invariant formulation of Moller-Plesset (MP) perturbation theory, analytical energy gradients have been formulated and implemented for local second order MP (LMP2) calculations. The geometry-dependent truncation terms of the LMP2 energy have to be taken into account. This leads to a set of coupled-perturbed localization (CPL) equations which must be solved together with the coupled-perturbed Hartree-Fock (CPHF) equations. In analogy to the conventional non-local theory, the repeated solution of these equations for each degree of freedom can be avoided by using the z-vector method of Handy and Schaefer. Explicit equations are presented for the Pipek-Mezey localization. Test calculations on smaller organic molecules demonstrate that the local approximations introduce only minor changes of computed equilibrium structures.
- Journal
- Journal of Chemical Physics
- Volume
- 108
- Issue
- 13
- Year
- 1998
- Start Page
- 5185-5193
- URL
- https://dx.doi.org/10.1063/1.475955
- ISBN/ISSN
- 1089-7690; 0021-9606
- DOI
- 10.1063/1.475955