A comparative basis‐set study of NeH+ using coupled‐cluster techniques

Abstract

AbstractUnrestricted Hartree‐Fock, coupled‐cluster calculations are reported for the ground state of NeH+ using atomic basis sets of increasing size and accuracy for both Ne and H. The goal is to determine the basis set and coupled‐cluster level of calculation needed to obtain a NeH+ potential energy curve of known accuracy. Here, it is shown that calculations using a quintuple zeta basis at the coupled‐cluster singles and doubles level with noniterative triples, CCSD(T), predict a Ne—H bond dissociation energy that is within about 0.01 eV of the exact Born–Oppenheimer molecular electronic structure result. Spectroscopic constants determined using the Simons–Parr–Finlan procedure are found to be in very good agreement with the experimental results. Calculations at the augmented quadruple zeta level for the two lowest triplet excited states of the NeH+ species are presented. Both of these states separate into ground‐state Ne+ and H(1s). The resulting potential curves predict stable minima at the SCF, CCSD, and CCSD(T) levels with dissociation energies of about 0.07 eV. Spectroscopic constants from the potential curves and dissociation constants are reported. © 1994 John Wiley & Sons, Inc.