title: Anharmonic Vibrational Analysis for the Propadienylidene Molecule (H2C═C═C:).
abstract: Maier et al. found that photolysis of singlet cyclopropenylidene (1S) in a matrix yields triplet propargylene (2T), which upon further irradiation is converted to singlet propadienylidene (vinylidenecarbene, 3S). Their discovery was followed by interstellar identification of 3S by Cernicharo et al. An accurate quartic force field for propadienylidene (3S) has been determined employing the ab initio coupled-cluster (CC) with single and double excitations and perturbative triple excitations [CCSD(T)] method and the correlation-consistent core-valence quadruple-ζ (cc-pCVQZ) basis set. Utilizing vibrational second-order perturbation theory (VPT2), vibration-rotation coupling constants, rotational constants, centrifugal distortion constants, vibrational anharmonic constants, and fundamental vibrational frequencies are determined. The predicted fundamental frequencies for 3S as well as its (13)C and deuterium isotopologues are in good agreement with experimental values. The theoretical zero-point vibration corrected rotational constants B0 are consistent with experimental values within 0.3% of errors. The isotopic shifts of B0 are in close to exact agreement with experimental observations. The mean absolute deviation between theoretical anharmonic and experimental fundamental vibrational frequencies for 24 modes (excluding CH2 s-str.) is only 2.6 cm(-1). The isotopic shifts of the vibrational frequencies are also in excellent agreement with the available experimental values. However, a large discrepancy is observed for the CH2 symmetric stretch, casting doubt on the experimental assignment for this mode.
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Qunyan
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Hao
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Jeremiah J
authors.initials: JJ
authors.lastname: Wilke
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Simmonett
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Qianshu
authors.initials: Q
authors.lastname: Li
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: De-Cai
authors.initials: DC
authors.lastname: Fang
authors.affiliation: Institute of Chemical Physics, Beijing Institute of Technology, Beijing, P. R. China 100081, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, College of Chemistry, Beijing Normal University, Beijing, P. R. China 100875, and Center for Computational Quantum Chemistry, South China Normal University, Guangzhou, P. R. China 510631.
authors.forename: Henry F
authors.initials: HF
authors.lastname: Schaefer