H/sub 3/ /sup +/: Ab initio calculation of the vibration spectrum
The vibration spectrum of H/sub 3/ /sup +/ is calculated from the representation of a previously reported (J. Chem Phys. 60, 4251 (1974)) ab initio potential-energy surface in a fifth degree Simons--Parr--Finlan (SPF) expansion. Morse- and harmonic-oscillator basis functions are used to describe the motions of the three oscillators and the Harris--Engerholm--Gwinn quadrature technique is used to obtain matrix elements of the Hamiltonian in the basis of vibrational configurations. Our variational method is thus analogous to configuration--interaction calculations for electronic states. The ground state is found to have a zero-point energy of 4345 cm/sup -1/ and a vibrationally averaged geometry of R/sub 1/=R/sub 2/=0.91396 A, theta=60.0012degree, where theta is the angle between the two equivalent bonds. The transition frequencies for the E and A/sub 1/ fundamentals are nu-bar/sub E/=2516 cm/sup -1/ and nu-bar/sub A/=3185 cm/sup -1/ and those for the corresponding first overtones of the bending mode are 2nu-bar/sub E/=5004 +- 4 cm/sup -1/ and 2nu-bar/sub A/=4799 cm/sup -1/. The first overtone of the breathing mode is 6264 cm/sup -1/. The first-excited A/sub 1/ vibration state is metastable with a dipole--radiation lifetime of 3 sec. Transition frequencies, Einstein coefficients, and lifetimes are reported for a total of 21 transitions. Analysis of results for Dunham number and normal-coordinate expansions in comparison with those for SPF expansion show the latter to be superior for ab initio vibrational calculations. A scheme for possible direct measurement of the fundamental A/sub 1/ and E vibrational bands is suggested. (AIP)
- Research Organization:
- Department of Chemistry, State University of New York, Stony Brook, New York 11794
- OSTI ID:
- 7346821
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 65:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROGEN IONS 3 PLUS
INFRARED SPECTRA
METASTABLE STATES
POTENTIAL ENERGY
VARIATIONAL METHODS
VIBRATIONAL STATES
CATIONS
CHARGED PARTICLES
ENERGY
ENERGY LEVELS
EXCITED STATES
HYDROGEN IONS
IONS
MOLECULAR IONS
SPECTRA
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory