Analytic cubic and quartic force fields using density-functional theory

作者：Ringholm Magnus^*; Jonsson Dan; Bast Radovan; Gao Bin; Thorvaldsen Andreas J; Ekstrom Ulf; Helgaker Trygve; Ruud Kenneth

来源：Journal of Chemical Physics, 2014, 140(3): 034103.

DOI：10.1063/1.4861003

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.

• 出版日期2014-1-21