Classical and nonclassical forms of protonated acetylene, C/sub 2/H/sup +//sub 3/. Structures, vibrational frequencies, and infrared intensities from explicitly correlated wave functions

Journal Article · Mon Sep 15 04:00:00 EDT 1986 · J. Chem. Phys.; (United States)

OSTI ID:5139213

Lee, T J; Schaefer, III, H F

The vibrational frequencies and IR intensities of C/sub 2/H/sup +//sub 3/ and C/sub 2/D/sup +//sub 3/ have been predicted using the methods of a-italicb-italic i-italicn-italici-italict-italici-italico-italic molecular quantum mechanics. Specifically, configuration interaction (CI) wave functions have been constructed from double zeta plus polarization (DZ+P) basis sets. In addition, a much larger basis set, triple zeta plus diffuse plus double polarization, has been used at the self-consistent-field (SCF) level of theory. The results are qualitatively similar to those (at much lower levels of theory) reported earlier by Raine and Schaefer. At the highest level of theory, CI including all single, double, and triple excitations (213 780 configurations for the classical structure), the nonclassical structure is the lower by only 0.7 kcal/mol.

• Research Organization: Department of Chemistry and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 5139213
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 85:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ACETYLENE
ALKYNES
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CONFIGURATION INTERACTION
CORRELATIONS
ELECTRON CORRELATION
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
HYDROCARBONS
HYDROGENATION
INFRARED SPECTRA
IONS
MOLECULAR IONS
ORGANIC COMPOUNDS
SELF-CONSISTENT FIELD
SPECTRA
VIBRATIONAL STATES
WAVE FUNCTIONS