Torsion-wagging tunneling and vibrational states in hydrazine determined from its ab initio potential energy surface

2012 ◽  
Vol 136 (17) ◽  
pp. 174301 ◽  
Author(s):  
Wiesław Łodyga ◽  
Jan Makarewicz
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Vibrational States

scholarly journals Computational study of the rovibrational spectrum of H2O-HF

2021 ◽  
Author(s):  
Dominika VIGLASKA ◽  
Xiao-Gang Wang ◽  
Tucker CARRINGTON ◽  
David Tew
Keyword(s):  
Experimental Data ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Study ◽  
Energy Levels ◽  
Dissociation Limit ◽  
Lanczos Algorithm ◽  
Vibrational States

In this paper we report rovibrational energy levels, transition frequencies, and intensities computed for H2O-HF using a new ab initio potential energy surface and compare with available experimental data. We use the rigid monomer approximation. A G4 symmetry-adapted Lanczos algorithm and an uncoupled product basis are employed. The rovibrational levels are computed up to J = 4. The new analytic 9-D potential is �t to 39771 counterpoise corrected CCSD(T)(F12*)/augcc- pVTZ energies and reduces to the sum of uncoupled H2O and HF potentials in the dissociation limit. On the new potential better agreement with experiment is obtained by re-assigning the R(1) transitions of two vibrational states.

scholarly journals Ab Initio Ro-Vibrational Structure of the C2? Isotopes of H2O+

1992 ◽  
Vol 45 (5) ◽  
pp. 651 ◽  
Author(s):  
F Wang ◽  
EI von Nagy-Felsobuki
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Force Field ◽  
Ab Initio ◽  
Excellent Agreement ◽  
Energy Surface ◽  
Variational Calculation ◽  
Vibrational Structure ◽  
Vibrational States ◽  
Normal Coordinate

The ro-vibrational structures of the C2" isotopes ofH20+ have been calculated from variational solution of the normal coordinate Eckart-Watson Hamiltonian. The calculations use the discrete ab initio potential energy surface of Weis et al. (1989). Where comparisons can be made, the assignment of the vibrational states is in excellent agreement with experiment and with the ab initio variational calculation of Weis et al., who utilised a different force field and an internal coordinate nuclear Hamiltonian (instead of the Eckart-Watson amiltonian). Furthermore, the calculated rotational levels of the ground and the first excited vibrational states of H20+ and D20+ are in excellent agreement with experiment.

scholarly journals Full-Dimensional Ab Initio Potential Energy Surface and Vibrational Energy Levels of Li2H

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 26
Author(s):  
Michiko Ahn Furudate ◽  
Denis Hagebaum-Reignier ◽  
Gwang-Hi Jeung
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Configuration Interaction ◽  
Energy Surface ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Vibrational States ◽  
Configuration Interaction Method ◽  
Vibrational Energy Levels

We built a full-dimensional analytical potential energy surface of the ground electronic state of Li2H from ca. 20,000 ab initio multi-reference configuration interaction calculations, including core–valence correlation effects. The surface is flexible enough to accurately describe the three dissociation channels: Li (2s 2S) + LiH (1Σ+), Li2 (1Σg+) + H (1s 2S) and 2Li (2s 2S) + H (1s 2S). Using a local fit of this surface, we calculated pure (J = 0) vibrational states of Li2H up to the barrier to linearity (ca. 3400 cm−1 above the global minimum) using a vibrational self-consistent field/virtual state configuration interaction method. We found 18 vibrational states below this barrier, with a maximum of 6 quanta in the bending mode, which indicates that Li2H could be spectroscopically observable. Moreover, we show that some of these vibrational states are highly correlated already ca. 1000 cm−1 below the height of the barrier. We hope these calculations can help the assignment of experimental spectra. In addition, the first low-lying excited states of each B1, B2 and A2 symmetry of Li2H were characterized.

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