title: Analytic cubic and quartic force fields using density-functional theory.
abstract: We present the first analytic implementation of cubic and quartic force constants at the level of Kohn-Sham density-functional theory. The implementation is based on an open-ended formalism for the evaluation of energy derivatives in an atomic-orbital basis. The implementation relies on the availability of open-ended codes for evaluation of one- and two-electron integrals differentiated with respect to nuclear displacements as well as automatic differentiation of the exchange-correlation kernels. We use generalized second-order vibrational perturbation theory to calculate the fundamental frequencies of methane, ethane, benzene, and aniline, comparing B3LYP, BLYP, and Hartree-Fock results. The Hartree-Fock anharmonic corrections agree well with the B3LYP corrections when calculated at the B3LYP geometry and from B3LYP normal coordinates, suggesting that the inclusion of electron correlation is not essential for the reliable calculation of cubic and quartic force constants.
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
authors: Magnus
authors: M
authors: Ringholm
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
authors: Dan
authors: D
authors: Jonsson
authors: Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm, Sweden and PDC Center for High Performance Computing, Royal Institute of Technology, S-10044 Stockholm, Sweden.
authors: Radovan
authors: R
authors: Bast
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
authors: Bin
authors: B
authors: Gao
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
authors: Andreas J
authors: AJ
authors: Thorvaldsen
authors: Center for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway.
authors: Ulf
authors: U
authors: Ekström
authors: Center for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway.
authors: Trygve
authors: T
authors: Helgaker
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
authors: Kenneth
authors: K
authors: Ruud
mesh_terms: D000465:Algorithms; D000814:Aniline Compounds / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D004980:Ethane / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D000814:Aniline Compounds; D001554:Benzene; D004980:Ethane; D008697:Methane; C023650:aniline