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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.

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.

[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).