Analytical energy gradients for local second-order Møller-Plesset perturbation theory using density fitting approximations.
An efficient method to compute analytical energy derivatives for local second-order Møller-Plesset perturbation energy is presented. Density fitting approximations are employed for all 4-index integrals and their derivatives. Using local fitting approximations, quadratic scaling with molecular size and cubic scaling with basis set size for a given molecule is achieved. The density fitting approximations have a negligible effect on the accuracy of optimized equilibrium structures or computed energy differences. The method can be applied to much larger molecules and basis sets than any previous second-order Møller-Plesset gradient program. The efficiency and accuracy of the method is demonstrated for a number of organic molecules as well as for molecular clusters. Examples of geometry optimizations for molecules with 100 atoms and over 2000 basis functions without symmetry are presented.
Schütz
Martin
M
Institut fur Theoretische Chemie, Universitat Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany. schuetz@theochem.uni-stuttgart.de
Werner
Hans-Joachim
HJ
Lindh
Roland
R
Manby
Frederick R
FR