The {tilde {ital A}}{sup 1}{ital A}{sub {ital u}} state and the {ital T}{sub 2} potential surface of acetylene: Implications for triplet perturbations in the fluorescence spectra of the {tilde {ital A}} state

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.471658· OSTI ID:284260

Sherrill, C D; Vacek, G; Yamaguchi, Y; Schaefer, III, H F ^[1]; Stanton, J F ^[2]; Gauss, J ^[3]

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1. Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)
2. Institute for Theoretical Chemistry, Departments of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)
3. Lehrstuhl fuer Theoretische Chemie, Institut fuer Physikalische Chemie, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

The {ital cis}{endash}{ital trans} isomerization reaction on the {ital T}{sub 2} surface of acetylene and the lowest excited singlet state of acetylene, {tilde {ital A}}{sup 1}{ital A}{sub {ital u}}, are investigated by {ital ab} {ital initio} electronic structure theory. We report optimized geometries, dipole moments, and harmonic vibrational frequencies of stationary points and adiabatic energy differences between them using basis sets as large as triple-{zeta} plus double polarization with higher angular momentum functions, TZ(2{ital df},2{ital pd}), and theoretical methods up to coupled-cluster singles and doubles with a perturbative triples correction [CCSD(T)] and the equation-of-motion coupled-cluster method (EOM-CCSD). Our theoretical predictions should aid the interpretation of observations from a series of recent spectroscopic studies involving excited electronic states of acetylene. In particular, the present theoretical results rule out several possible explanations for the anomalous sudden increase in detectable Zeeman anticrossings reported by Dupr{acute e} {ital et} {ital al}. [Chem. Phys. {bold 152}, 293 (1991)]. {copyright} {ital 1996 American Institute of Physics.}

• DOE Contract Number: FG05-94ER14428
• OSTI ID: 284260
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 21 Vol. 104; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACETYLENE
DIPOLE MOMENTS
ELECTRONIC STRUCTURE
FLUORESCENCE
ISOMERIZATION
POTENTIAL ENERGY
QUANTUM CHEMISTRY
SPECTRA
VIBRATIONAL STATES