title: Analytical energy gradients for local second-order Møller-Plesset perturbation theory using density fitting approximations.
abstract: 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.
authors.affiliation: Institut fur Theoretische Chemie, Universitat Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany. schuetz@theochem.uni-stuttgart.de
authors.forename: Martin
authors.initials: M
authors.lastname: Schütz
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Werner
authors.forename: Roland
authors.initials: R
authors.lastname: Lindh
authors.forename: Frederick R
authors.initials: FR
authors.lastname: Manby