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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.

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.

[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).