High level [ital ab] [ital initio] study on the ground state potential energy hypersurface of the HCO[sup +]--COH[sup +] system

Journal Article · Mon Nov 14 23:00:00 EST 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.468023· OSTI ID:7122245

Yamaguchi, Y; Richards, Jr, C A; Schaefer, III, H F ^[1]

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1. Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

The ground state potential energy hypersurface of the HCO[sup +]--COH[sup +] system has been reinvestigated systematically using high level [ital ab] [ital initio] electronic structure theory. The geometries and physical properties of the two equilibrium and one isomerization transition state structures were determined at the self-consistent-field (SCF), configuration interaction with single and double excitations (CISD), coupled cluster with single and double excitations (CCSD), and CCSD with perturbative triple excitations [CCSD(T)] levels of theory with nine basis sets. First, the optimized geometries of the three stationary points at twenty eight (28) levels of theory were discussed. Second, the characteristics and responses of the molecular orbitals (MOs) with respect to the normal coordinates have been elucidated via energy derivative analysis technique. Third, dipole moments, harmonic vibrational frequencies, and infrared (IR) intensities were described. Finally, the relative energies among the stationary points have been compared. At the highest level of theory, CCSD(T) using triple zeta plus double polarization with diffuse and higher angular momentum functions [TZ2P([ital f],[ital d])+diff] basis set, the linear HCO[sup +] molecule is found to be 39.7 kcal/mol [37.7 kcal/mol with zero-point vibrational energy (ZPVE) correction] lower in energy relative to the linear COH[sup +] molecule. At the same level of theory the activation energy for the isomerization reaction HCO[sup +][r arrow]COH[sup +] is predicted to be 76.9 kcal/mol (72.6 kcal/mol with the ZPVE correction). Once the COH[sup +] species is formed, therefore, it should be reasonably stable with respect to the isomerization reaction at low temperatures.

• DOE Contract Number: FG05-94ER14428
• OSTI ID: 7122245
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 101:10; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664100* -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
664200 -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ACYL RADICALS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COMPLEXES
COUPLING
DIPOLES
ELECTRONIC EQUIPMENT
ELECTRONIC STRUCTURE
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EQUILIBRIUM
EQUIPMENT
EXCITATION
FORMYL RADICALS
GEOMETRY
GROUND STATES
HARMONIC OSCILLATORS
INFRARED SPECTRA
INTERSTELLAR SPACE
IONS
ISOMERIZATION
MATHEMATICS
MOLECULAR IONS
MULTIPOLES
OPTIMIZATION
OSCILLATORS
PHYSICAL PROPERTIES
POTENTIAL ENERGY
RADICALS
SPACE
SPECTRA