Toward spectroscopically accurate global ab initio potential energy surface for the acetylenevinylidene isomerization
Abstract
A new fulldimensional global potential energy surface (PES) for the acetylenevinylidene isomerization on the ground (S{sub 0}) electronic state has been constructed by fitting ∼37 000 highlevel ab initio points using the permutation invariant polynomialneural network method with a root mean square error of 9.54 cm{sup −1}. The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm{sup −1} above the zeropoint energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counterrotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction.
 Authors:
 Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
 (China)
 Publication Date:
 OSTI Identifier:
 22415426
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACETYLENE; ALGORITHMS; GROUND STATES; HAMILTONIANS; ISOMERIZATION; NEURAL NETWORKS; POLYNOMIALS; POTENTIAL ENERGY; REPRODUCTION; SURFACES; VIBRATIONAL STATES; WAVE FUNCTIONS
Citation Formats
Han, Huixian, School of Physics, Northwest University, Xi’an, Shaanxi 710069, Li, Anyang, and Guo, Hua, Email: hguo@unm.edu. Toward spectroscopically accurate global ab initio potential energy surface for the acetylenevinylidene isomerization. United States: N. p., 2014.
Web. doi:10.1063/1.4904859.
Han, Huixian, School of Physics, Northwest University, Xi’an, Shaanxi 710069, Li, Anyang, & Guo, Hua, Email: hguo@unm.edu. Toward spectroscopically accurate global ab initio potential energy surface for the acetylenevinylidene isomerization. United States. doi:10.1063/1.4904859.
Han, Huixian, School of Physics, Northwest University, Xi’an, Shaanxi 710069, Li, Anyang, and Guo, Hua, Email: hguo@unm.edu. 2014.
"Toward spectroscopically accurate global ab initio potential energy surface for the acetylenevinylidene isomerization". United States.
doi:10.1063/1.4904859.
@article{osti_22415426,
title = {Toward spectroscopically accurate global ab initio potential energy surface for the acetylenevinylidene isomerization},
author = {Han, Huixian and School of Physics, Northwest University, Xi’an, Shaanxi 710069 and Li, Anyang and Guo, Hua, Email: hguo@unm.edu},
abstractNote = {A new fulldimensional global potential energy surface (PES) for the acetylenevinylidene isomerization on the ground (S{sub 0}) electronic state has been constructed by fitting ∼37 000 highlevel ab initio points using the permutation invariant polynomialneural network method with a root mean square error of 9.54 cm{sup −1}. The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm{sup −1} above the zeropoint energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counterrotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction.},
doi = {10.1063/1.4904859},
journal = {Journal of Chemical Physics},
number = 24,
volume = 141,
place = {United States},
year = 2014,
month =
}

Isomerization reactions on the lowest potential energy hypersurface of triplet vinylidene and triplet acetylene
Triplet vinylidene, first predicted to have a sizeable barrier to unimolecular rearrangement in 1978 by theory, has now been observed under three different sets of experimental conditions. In order to quantitatively characterize the potential energy hypersurface of triplet vinylidene and triplet acetylene, highlevel [ital ab] [ital initio] quantum mechanical methods have been employed. Basis sets as large as triple zeta plus two sets of polarization functions augmented with higher angular momentum functions [TZ(2[ital df],2[ital pd])] have been utilized in conjunction with correlated methods as sophisticated as the coupled cluster approach including all single, double, and perturbative triple excitations [CCSD(T)]. Ofmore » 
An Accurate Global Ab Initio Potential Energy Surface for the X(1)A' Electronic State of HOBr
A global, analytical potential energy surface for the ground electronic state of HOBr has been determined using highly correlated multireference configuration interaction wave functions and explicit basis set extrapolations of large correlation consistent basis sets. The ab initio data have been fit to an analytical functional form that accurately includes both the HOBr and HBrO minima, as well as all dissociation asymptotes. Small adjustments to this surface are made based on the limited experimental data available and by indirectly taking into account the effects of spinorbit coupling on the OH+Br dissociation channel. Vibrational energy levels are calculated variationally for bothmore » 
An accurate global ab initio potential energy surface for the X {sup 1}A{sup '} electronic state of HOBr
A global, analytical potential energy surface for the ground electronic state of HOBr has been determined using highly correlated multireference configuration interaction wave functions and explicit basis set extrapolations of large correlation consistent basis sets. The ab initio data have been fit to an analytical functional form that accurately includes both the HOBr and HBrO minima, as well as all dissociation asymptotes. Small adjustments to this surface are made based on the limited experimental data available and by indirectly taking into account the effects of spinorbit coupling on the OH+Br dissociation channel. Vibrational energy levels are calculated variationally for bothmore »