title: A high-precision ab initio determination of the equilibrium geometry and force field of HOC+.
abstract: Ab initio molecular orbital theory is used to determine if the molecular ion HOC+ is linear (as are the isoelectronic species HCN, HNC, HCO+, etc.), or if it is quasilinear.  Near the Hartree-Fock limit the molecule is either linear, or very close to linear.  Electron correlation favors the linear geometry, leading to the unequivocal prediction of a linear molecule.  Detailed comparisons between HOC+ and isoelectronic HNC show an apparent lack of convergence in the bending potential for the former which is remedied by the addition of f functions to the basis set.  The HOC+ potential energy surface is computed in the bending and bend-stretch coordinates and fit to an analytical function.  Use of this function to compute the rotation-vibration energies results in improved agreement with experiment relative to previous potentials by nearly two orders of magnitude, as documented in the accompanying paper.
authors.affiliation: Molecular Research Institute, Palo Alto, California 94304, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: DeFrees
authors.forename: P R
authors.initials: PR
authors.lastname: Bunker
authors.forename: J S
authors.initials: JS
authors.lastname: Binkley
authors.forename: A D
authors.initials: AD
authors.lastname: McLean
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002412:Cations; D005118:Extraterrestrial Environment; D005561:Formates / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D007536:Isomerism; D015394:Molecular Structure
chemical_list: D002412:Cations; D005561:Formates; D006838:Hydrocarbons; C106724:oxomethylium