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Manuscript Title: Determination of potential energy surfaces of linear triatomics from vibration-rotation spectra: an inversion method applied to CO2.
Authors: H. Romanowski, M.A. Ratner, R.B. Gerber
Program title: RKRINV
Catalogue identifier: ABDR_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 51(1988)161
Programming language: Fortran.
Computer: HARRIS 1000.
Peripherals: disc.
Keywords: Molecular, Potential energy surface, Vibrational, Rotational spectroscopy, Vibrational-rotational Energies, Anharmonicity, Centrifugal distortion, Vibrational coupling, Vibrational-rotational Coupling, Semiclassical Self-consistent-field (scscf) calculations, Perturbation theory, Rkr inversion.
Classification: 16.3.

Nature of problem:
The inversion of vibrational-rotational energies to obtain potential energy surface for polyatomic molecule is described. The method described is the first non-fitting one which gives unique potential surface from experimental data.

Solution method:
The semiclassical self-consistent-field (SCSCF) method is used to reduce coupled vibrational hamiltonian to a set of effective one-dimensional ones. The RKR inversion method is then employed to obtain turning points of the effective one-dimensional potential curves. The coupling between modes is assumed to be pairwise and is extracted from SCF averages numerically.

Restrictions:
The program is written for a linear symmetric three-atomic molecule. (Can be easily extended to any three-atomic molecule.)

Running time:
Depends on the number of vibrational levels involved. It varies between 100-150 CPU mins. on a HARRIS 1000 computer (only SCF-RKR part).