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Manuscript Title: DVR3D: for the fully pointwise calculation of ro-vibrational spectra of triatomic molecules.
Authors: J. Tennyson, J.R. Henderson, N.G. Fulton
Program title: ROTLEV3
Catalogue identifier: ADAL_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 86(1995)175
Programming language: Fortran.
Computer: CONVEX C3800.
Operating system: UNIX.
Keywords: Molecular physics, Vibrations, Rotationally excited State, Coriolis coupling, Secondary variational Method, Sparse matrix, Vectorised.
Classification: 16.3.

Subprograms used:
Cat Id Title Reference
ACNE_v2_0 DVR3DRJ CPC 86(1995)175

Nature of problem:
ROTLEV3 performs the second step in a two-step variational calculation for the bound ro-vibrational levels of a triatomic system represented in either Jacobi or unsymmetrised Radau coordinates [1].

Solution method:
A basis is constructed from the solutions of the Coriolis decoupled problem provided by DVR3DRJ [2]. The angular coordinate is transformed back to a basis set representation [3]. The sparse Hamiltonian matrix can be diagonalised iteratively or in core.

Restrictions:
The size of matrix that can practically be diagonalised. ROTLEV3 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 DVR3DRJ [2]. ROTLEV3 can provide data to drive DIPOLE3 [4].

Running time:
Case dependent. The sample data takes 44 sec for a J=1 calculation on the Convex C3800.

References:
[1] J. Tennyson and B.T. Sutcliffe, Mol. Phys. 58(1986)1067.
[2] J. Tennyson, J.R. Henderson and N.G. Fulton, first program, this article (DVR3DRJ).
[3] J. Tennyson, J. Chem. Phys. 98(1993)9658.
[4] J. Tennyson, J.R. Henderson and N.G. Fulton, fourth program, this article (DIPOLE3).