Programs in Physics & Physical Chemistry
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|Manuscript Title: TRIATOM: for the calculaton of ro-vibrational spectra of triatomic molecules.|
|Authors: J. Tennyson, S. Miller, C.R. Le Sueur|
|Program title: TRIATOM|
|Catalogue identifier: ABJW_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|
|Keywords: Molecular physics, Vibration, Ro-vibrational, Body-fixed, Finite basis Representation, Gaussian quadrature, Variational, Vectorised.|
Nature of problem:
TRIATOM calculates the bound ro-vibrational levels of a triatomic system using the generalised body-fixed coordinates developed by Sutcliffe and Tennyson .
A basis is constructed as a product of radial (either Morse oscillator- like or spherical oscillator) functions and associated Legendre polynomials for the bending coordinate, with rotation matrices carrying the rotational motion. A secular matrix is constructed using Gaussian quadrature and diagonalised to give solutions. Input can be direct from SELECT . TRIATOM provides data necessary to drive ROTLEVD  and DIPOLE .
The size of matrix that can practically be diagonalised. TRIATOM 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.
A user supplied subroutine containing the potential energy as an analytic function (optionally a Legendre polynomial expansion) is a program requirement.
Highly case dependent. The sample data takes 17 sec for J=0 and 30 sec for J=1 (Coriolis decoupled) on the Convex C3840.
|||B.T. Sutcliffe and J. Tennyson, Intern. J. Quantum Chem. 29(1991)183|
|||J. Tennyson, S. Miller, C.R. Le Sueur, this article, second program (SELECT).|
|||J. Tennyson, S. Miller, C.R. Le Sueur, this article, third program (ROTLEVD)|
|||J. Tennyson, S. Miller, C.R. Le Sueur, this article, fourth program (DIPOLE).|
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