title: Analytical Gradients of Hartree-Fock Exchange with Density Fitting Approximations.
abstract: We extend the local exchange (LK) algorithm [Aquilante, F.; Pedersen, T. B.; Lindh, R. J. Chem. Phys.2007, 126, 194106] to the calculation of analytical gradients with density fitting. We discuss the features of the screening procedure and demonstrate the possible advantages of using this formulation, which is easily interfaced to a standard integral-direct gradient code. With auxiliary basis sets obtained from Cholesky decomposition of atomic or molecular integral blocks with a decomposition threshold of 10(-4)Eh, typical errors due to the density fitting in bond lengths, bond angles, and dihedral angles are 0.1 pm, 0.1°, and 0.5°, respectively. The overall speedup of geometry optimizations is about 1 order of magnitude for atomic natural-orbital-type basis sets but much less pronounced for correlation-consistent basis sets.
authors.affiliation: Department of Theoretical Chemistry, Chemical Center, University of Lund, P.O. Box 124 S-221 00 Lund, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Boström
authors.affiliation: Center for Biomolecular Nanotechnologies @UNILE, Italian Institute of Technology (IIT), Via Barsanti, I-73010 Arnesano (LE), Italy.|Department of Chemistry - Ångström, The Theoretical Chemistry Programme, Uppsala University, P.O. Box 518, SE-751 20 Uppsala, Sweden.
authors.forename: Francesco
authors.initials: F
authors.lastname: Aquilante
authors.affiliation: Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway.
authors.forename: Thomas Bondo
authors.initials: TB
authors.lastname: Pedersen
authors.affiliation: Department of Chemistry - Ångström, The Theoretical Chemistry Programme, Uppsala University, P.O. Box 518, SE-751 20 Uppsala, Sweden.
authors.forename: Roland
authors.initials: R
authors.lastname: Lindh