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Manuscript Title: TRIATOM: for the calculation of ro-vibrational spectra of triatomic molecules.
Authors: J. Tennyson, S. Miller, C.R. Le Sueur
Program title: ROTLEVD
Catalogue identifier: ABJY_v2_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 75(1993)339
Programming language: Fortran.
Computer: Convex C3840.
Operating system: BSD UNIX.
Word size: 32
Peripherals: disc.
Keywords: Molecular physics, Vibrations, Rotationally excited State, Coriolis coupling, Secondary variational Method, Sparse matrix, Vectorised.
Classification: 16.3.

Subprograms used:
Cat Id Title Reference
ABJW_v2_0 TRIATOM CPC 75(1993)339
ACNC_v1_0 DVR1D CPC 75(1993)339

Nature of problem:
ROTLEVD performs the second step in a two-step variational calculation for the bound ro-vibrational levels of a triatomic system [1].

Solution method:
A basis is constructed from the solutions, optionally energy ordered [2], of the Coriolis decoupled problem. The resulting sparse matrix is then diagonalised to give the solutions.

Restrictions:
The size of matrix that can practically be diagonalised. ROTLEVD dimensions arrays dynamically at execution time and in the present version the total space available is a single parameter which can be reset as required.

Unusual features:
Most data is read directly from TRIATOM [3] or DVR1D [4]. ROTLEVD can provide data to drive DIPOLE [5].

Running time:
Case dependent. The sample data takes 171 sec for a J=1 calculation on the Convex C3840.

References:
[1] J. Tennyson and B.T. Sutcliffe, Mol. Phys. 58(1986)1067.
[2] B.T. Sutcliffe, J. Tennyson, S. Miller, Comp.Phys.Comm. 51(1988)73.
[3] J. Tennyson, S. Miller, C.R. Le Sueur, this article, first program (TRIATOM).
[4] J.R. Henderson and J. Tennyson, Comp. Phys. Commun., (following article).
[5] J. Tennyson, S. Miller, C.R. Le Sueur, this article, fourth program (DIPOLE).