A full-dimensional analytical potential energy surface for the F+CH_4→HF+CH_3 reaction

• 作 者: 杨传路 王美山 刘文旺 张志红 马晓光
• 机 构: School of Physics and Optoelectronic Engineering,Ludong University,
• 出 处: Chinese Physics B
• 发表日期: 2013年06期
• 关键词: constants saddle unrestricted vibrational triple derivation fitted fitting repro

A full-dimensional analytical potential energy surface(APES) for the F + CH4 →HF + CH3 reaction is developed based on 7127 ab initio energy points at the unrestricted coupled-cluster with single,double,and perturbative triple excitations.The correlation-consistent polarized triple-split valence basis set is used.The APES is represented with a many-body expansion containing 239 parameters determined by the least square fitting method.The two-body terms of the APES are fitted by potential energy curves with multi-reference configuration interaction,which can describe the diatomic molecules(CH,H2,HF,and CF) accurately.It is found that the APES can reproduce the geometry and vibrational frequencies of the saddle point better than those available in the literature.The rate constants based on the present APES support the experimental results of Moore et al.[Int.J.Chem.Kin.26,813(1994)].The analytical first-order derivation of energy is also provided,making the present APES convenient and efficient for investigating the title reaction with quasiclassical trajectory calculations.

A full-dimensional analytical potential energy surface (APES) for the F + CH4 → HF + CH3 reaction is developed based on 7127 ab initio energy points at the unrestricted coupled-cluster with single, double, and perturbative triple excitations.The correlation-consistent polarized triple-split valence basis set is used. The APES is represented with a large-body expansion containing 239 parameters determined by the least square fitting method. The two-body terms of the APES are fitted by potential energy curves with multi-reference configuration (CH, H2, HF, and CF) accurately. It is found that the APES can reproduce the geometry and vibrational frequencies of the saddle point better than those available in the literature. Rate constants based on the present invention APE support the experimental results of Moore et al. [Int. J. Chem. Kin. 26, 813 (1994)]. The analytical first-order derivation of energy is also provided, making the present APES convenient and e fficient for investigating the title reaction with quasiclassical trajectory calculations.