Calculation of vibrational energy levels of symmetric molecules from potential energy surface

doi:10.15372/aoo20150502

Cited by 2 publications

(1 citation statement)

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“…An account of the symmetry and the use of the irreducible tensor representation permitted obtaining an optimal non-redundant grid of nuclear geometries. One grid adapted for the analytical PES development up to the 6-th order (6412 geometries) has been constructed in the work using the geometry set generation technique already applied for other symmetric molecules. , Here, we use also extended grid of 78,739 geometries that unambiguously define the PES development up to 8-th order constructed by the same technique. These two grids of geometries allowed us to carry out ab initio electronic energy calculations for a wide range of nuclear displacements.…”

Section: Equilibrium Geometry and Analytical Form Of Pes And Dmsmentioning

confidence: 99%

First Full-Dimensional Potential Energy and Dipole Moment Surfaces of SF₆

et al. 2020

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A 15-dimensional analytical form for the potential energy and dipole moment surfaces of the SF6 molecule in the ground electronic state is obtained using ab initio methods. In order to calculate the equilibrium S-F distance, we applied coupled cluster CCSD(T) method and several versions of the correlation consistent basis sets -from valence triple-zeta (VTZ) and augmented valence triple-zeta (AVTZ) to core-valence quadruple-zeta (CVQZ) with Douglas-Kroll (DK) relativistic corrections that provided good agreement with empirical equilibrium value. Ab initio electronic energies on 15D grids of nuclear geometries are computed using CCSD(T) method with VTZ and CVQZ-DK basis sets. The analytical representation of the potential energy surface is determined through an expansion in symmetry adapted products of non-linear coordinates up to the 5-th order. The influence of additional redundant coordinates on the quality of the fit was investigated. Parameters of full dimensional dipole moment surfaces are determined up to the 4th order expansion in normal mode coordinates. For validation of ab initio results, the fundamental vibration frequencies and absorption cross-sections of the principal sulfur hexafluoride isotopolgue are calculated giving good agreement with cold (180 K) and room temperature ( 296 K) experimental spectra. Absorption cross-sections calculated from our preliminary line list agree much better with these observations than the simulations using SF6 line-by-line lists constructed from effective models included in currently available spectroscopic databases.

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Section: Equilibrium Geometry and Analytical Form Of Pes And Dmsmentioning

confidence: 99%