Comparison of theoretical methods for the determination of the protonation and deprotonation energies of ammonia, water, hydrogen fluoride, phosphine, hydrogen sulfide, hydrogen chloride and hydrogen cyanide

Abstract

The structures of the bases NH{sub 3}, H{sub 2}O, HF, PH{sub 3}, H{sub 2}S, HCl, and HCN and the corresponding protonated and deprotonated ions have been optimized by using second-order Moller-Plesset perturbation theory with the 6-31+G(d,p) basis. Basis set superposition errors for computed protonation and deprotonation energies of NH{sub 3} were evaluated for four different basis sets. Single-point calculations on all species were performed with the 6-31+G(2d,2p) basis using the following correlation methods: many-body (Moller-Plesset) perturbation theory at second (MP2), third (MP3), and fourth (MP4) order; the linearized coupled-cluster method (LCCM); the averaged coupled-pair functional (ACPF); configuration interaction with all single and double excitations (CISD); and CISD with the Davidson and the Pople corrections, all relative to a single-reference Hartree-Fock function.