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Manuscript Title: DVR3D: a program suite for the calculation of rotation-vibration spectra of triatomic molecules (DVR3DRJZ).
Authors: J. Tennyson, M.A. Kostin, P. Barletta, G.J. Harris, O.L. Polyansky, J. Ramanlal, N.F. Zobov.
Program title: DVR3DRJZ
Catalogue identifier: ADTB
Journal reference: Comput. Phys. Commun. 163(2004)85
Programming language: Fortran 90.
Computer: PC, Compaq, Sunfire V750 and V880, IBM p690 Regatta, SGI Origin 2000.
Operating system: UNIX, Linux, AIX.
RAM: Case dependent.
Keywords: Molecular spectra, Infrared, Microwave, Variational principle, Expectation values, Born-Oppenheimer approximation, Triatomic molecules, Perpendicular embedding.
PACS: 33.20, 39.30.
Classification: 16.3.

Other versions:
Cat Id Title Reference
ACNE DVR3D CPC 75(1993)379
ADAK DVR3D CPC 86(1995)175

Nature of problem:
DVR3DRJZ calculates the bound vibrational or Coriolis decoupled ro-vibrational states of a triatomic system in body-fixed Jacobi (scattering) or Radau coordinates [1,2].

Solution method:
All coordinates are treated in a discrete variable representation (DVR). The angular coordinate uses a DVR based on (associated) Legendre polynomials and the radial coordinates utilise a DVR based on either Morse oscillator-like or spherical oscillator functions. Intermediate diagonalisation and truncation is performed on the hierarchical expression of the Hamiltonian operator to yield the final secular problem. DVR3DRJZ provides the vibrational wavefunctions necessary for ROTLEV2, ROTLEV3B or ROTLEV3Z to calculate rotationally excited states, DIPOLE3 to calculate ro-vibrational transition strengths and XPECT3 to compute expectation values.

(1) The size of the final Hamiltonian matrix that can practically be diagonalised.
(2) The order of integration in the radial coordinates that can be dealt with within the machine exponent range. Some adjustment in the code may be necessary when large order Gauss-Laguerre quadrature is used.

Unusual features:
A user supplied subroutine containing the potential energy as an analytic function is a program requirement.

Additional comments:
The code has been extensively vectorised. A parallel version of the code, PDVR3D has been developed [1], contact the first author for details.
DVR3DRJZ forms part of the DVR3D suite of programs. The complete suite is catalogued under the identifier ADTI. The tar.gz file for ADTI contains sample input and output data which can be used to test all the programs in the suite.

Running time:
Case dependent but usually dominated by the final (3D) matrix diagonalisation. The test runs take minutes on a fast PC.

[1] H.Y. Mussa and J. Tennyson, Computer Phys. Comms., 128, 434(2000).
[2] J. Tennyson and B. T. Sutcliffe, Intern. J. Quantum Chem. 42(1992)941.