Accurate equilibrium inversion barrier of ammonia by extrapolation to the one-electron basis set limit

作者：Li Yong Qing^*; Song Peng; Ma Feng Cai

来源：Chinese Physics B, 2014, 23(2): 023301.

DOI：10.1088/1674-1056/23/2/023301

• inversion barrier
• ammonia
• complete basis set limit
• low-cost

A scheme based on treating uniform singlet-pair and triplet-pair interactions is suggested to extrapolate electron correlation energy of ammonia, calculated at two basis-set levels of ab initio theory in the infinite one-electron basis-set limit. The dual-level method is tested on the extrapolation of the full correlation in coupled-cluster singles and doubles and in the case also a noniterative perturbative correction for connected triple energies for the C-3v and D-3h structures of ammonia, with correlation-consistent basis sets of the type cc-pVXZ (X = D, T, Q, 5, 6) and aug-cc-pVXZ (X = D, T, Q, 5). For testing and comparison purposes, the energies reported by Klopper [J. Comput. Chem. 22 1306 (2001)] have been taken. From a corresponding extrapolation of CCSD(T)/AVXZ energies for X = 4, 5, we obtain total inversion barriers of 1833.87 cm(-1)/1832.33 cm(-1) for the two/three-parameter extrapolation rules, which are in good agreement with other theoretical extrapolation and empirical values in the literature.

• 出版日期2014-2
• 单位辽宁大学