XINCHUAN HUANG AND TIMOTHY J. LEE, MS 245-6, NASA Ames Research Center, Moffett Field, California 94035..
Purely ab initio CCSD(T) quartic force fields have been determined for the lowest triplet and singlet states of HO2+ ion with TZ-,QZ- and 5Z-level one-particle basis sets. After extrapolating to complete basis-set limit, small correction terms have now been incorporated, including core-correlation, scalar relativistic, and others. Anharmonic vibrational fundamentals and ro-vibrational spectroscopic constants are computed with perturbational and variational methods. Our best computed force field should give fundamentals to within \pm5 cm-1. In this talk we will present the procedure details and compare our results with previous work on this ion. Effects of small corrections and benchmark results on H2O will also be discussed.