Y. Pak et Rc. Woods, SPECTROSCOPIC CONSTANTS AND POTENTIAL-ENERGY FUNCTIONS OF OCCL-CLUSTER METHOD(, ONP, ONS+, ARCN+, OCS, AND NCCL USING THE COUPLED), The Journal of chemical physics, 107(13), 1997, pp. 5094-5102
Large basis set ab initio calculations have been carried out on the th
ree-dimensional near-equilibrium potential energy surfaces of the spec
troscopically unknown species OCCl+, ONP, ONS+, and ArCN+ and the isoe
lectronic reference molecules OCS and NCCl, using a correlation consis
tent polarized valence quadruple zeta (cc-pVQZ) basis set and the coup
led cluster method with single and double substitutions, augmented by
a perturbative estimate of triple excitations [CCSD(T)]. A complete se
t of spectroscopic constants for each species has been obtained from t
he CCSD(T)/cc-pVQZ potential energy surfaces using the standard second
-order perturbation theory formulas. In order to predict equilibrium b
ond distances of the unknown species as accurately as possible, their
resulting CCSD(T) structures have been corrected based on identical ca
lculations on both the diatomics CO, CN, NO, CS, CCl+, and NP and the
linear triatomics OCS and NCCl. The second-order spectroscopic constan
ts and anharmonic force fields for OCS and OCCl+ previously calculated
with the MP4SDQ and CISD(s) methods are in good agreement with the pr
esent CCSD(T) results. (C) 1997 American Institute of Physics.