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Manuscript Title: DVR1D: programs for mixed pointwise/basis set calculation of ro- vibrational spectra.
Authors: J.R. Henderson, J. Tennyson
Program title: DVR1D
Catalogue identifier: ACNC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 75(1993)365
Programming language: Fortran.
Computer: Convex C3840.
Operating system: BSD UNIX.
Word size: 32
Peripherals: disc.
Keywords: Molecular physics, Vibration, Ro-vibrational, Body-fixed, Discrete varaible Representation, Finite elements, Vectorised.
Classification: 16.3.

Nature of problem:
DVR1D calculates the bound vibrational levels of a triatomic system using body-fixed coordinates (either Jacobi or Radau) [1].

Solution method:
The angular coordinate is treated using a discrete variable representation (DVR) based on (associated) Legendre polynomials and the radial coordinates are represented by a basis constructed as a product of either Morse oscillator-like or spherical oscillator functions. Intermediate diagonalisation and truncation is used to construct the final secular problem. For rotationally excited states DVR1D provides data necessary to drive ROTLEV2 [2] or ROTLEVD [3].

Restrictions:
The size of matrix that can practically be diagonalised. DVR1D 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:
A user supplied subroutine containing the potential energy as an analytic function (optionally a Legendre polynomial expansion) is a program requirement.

Running time:
Case dependent but dominated by matrix diagonalisation. The sample data takes 23 sec for J=0 and 47 sec for J=1 (Coriolis decoupled) on the Convex C3840.

References:
[1] J. Tennyson and J.R. Henderson, J.Chem.Phys., 1989, 91,3815
[2] J.R. Henderson and J. Tennyson, this article, second program (ROTLEV2).
[3] J. Tennyson, S. Miller and C.R. Le Sueur, Comp. Phys. Commun., previous article.