Ringholm Magnus, Jonsson Dan, Bast Radovan, Gao Bin, Thorvaldsen Andreas J, Ekström Ulf, Helgaker Trygve, Ruud Kenneth
Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø-The Arctic University of Norway, 9037 Tromsø, Norway.
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.
J Chem Phys. 2014 Jan 21;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.
我们展示了在Kohn-Sham密度泛函理论层面上对立方和四次方力常数的首个解析实现。该实现基于一种开放式形式体系，用于在原子轨道基组中评估能量导数。此实现依赖于用于评估相对于核位移进行微分的单电子和双电子积分的开放式代码的可用性，以及交换关联核的自动微分。我们使用广义二阶振动微扰理论来计算甲烷、乙烷、苯和苯胺的基频，比较了B3LYP、BLYP和Hartree-Fock的结果。当在B3LYP几何结构和从B3LYP正规坐标进行计算时，Hartree-Fock非谐校正与B3LYP校正吻合良好，这表明对于立方和四次方力常数的可靠计算，包含电子相关并非必不可少。
