Ab initio calculation of anharmonic vibrational states of polyatomic systems:: Electronic structure combined with vibrational self-consistent field
Ab initio calculation of anharmonic vibrational states of polyatomic systems:: Electronic structure combined with vibrational self-consistent field
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DOI：
10.1063/1.479452
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发表时间：
1999-08-01
影响因子：
4.4
通讯作者：
Gerber, RB
中科院分区：
文献类型：
--
作者：
Chaban, GM;Jung, JO;Gerber, RB
提出了一种多原子分子振动光谱第一性原理计算算法，该算法将电子从头计算代码与振动自洽场（VSCF）方法以及VSCF的微扰理论扩展相结合。积分方法直接使用 VSCF 部分中从电子从头计算代码计算出的势能面上的点。不涉及分析势函数的拟合。该方法的一个关键要素是近似，即只有成对正常模式之间的相互作用才重要，而三元组或更多元组之间的相互作用可以忽略不计。人们发现这个假设在应用中很好地成立。新算法适用于H(2)O、Cl(-)(H(2)O) 和(H(2)O)(2) 的基本振动激发，使用电子结构的Moller-Plesset 方法。发现的振动频率与实验非常吻合。估计表明，这种电子从头算/VSCF 方法应该是可行的，具有合理的计算资源，可用于最多 10-15 个原子的系统的振动能量和波函数的全模式计算。通过与实验振动光谱进行比较，新方法对于测试电子结构代码的准确性也非常有用。 (C) 1999 年美国物理研究所。 [S0021-9606(99)01928-5]。
An algorithm for first-principles calculation of vibrational spectroscopy of polyatomic molecules is proposed, which combines electronic ab initio codes with the vibrational self-consistent field (VSCF) method, and with a perturbation-theoretic extension of VSCF. The integrated method directly uses points on the potential energy surface, computed from the electronic ab initio code, in the VSCF part. No fitting of an analytic potential function is involved. A key element in the approach is the approximation that only interactions between pairs of normal modes are important, while interactions of triples or more can be neglected. This assumption was found to hold well in applications. The new algorithm was applied to the fundamental vibrational excitations of H(2)O, Cl(-)(H(2)O), and (H(2)O)(2), using the Moller-Plesset method for the electronic structure. The vibrational frequencies found are in very good accord with experiments. Estimates suggest that this electronic ab initio/VSCF approach should be feasible, with reasonable computational resources, for all-mode calculations of vibrational energies and wave functions for systems of up to 10-15 atoms. The new method can be also very useful for testing the accuracy of electronic structure codes by comparing with experimental vibrational spectroscopy. (C) 1999 American Institute of Physics. [S0021-9606(99)01928-5].