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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_0Distribution format: gz | ||

Journal reference: Comput. Phys. Commun. 75(1993)339 | ||

Programming language: Fortran. | ||

Computer: Convex C3840. | ||

Operating system: BSD UNIX. | ||

Word size: 32 | ||

Peripherals: disc. | ||

Keywords: Molecular physics, Vibration, Ro-vibrational, Body-fixed, Finite basis Representation, Gaussian quadrature, Variational, Vectorised. | ||

Classification: 16.3. | ||

Subprograms used: | ||

Cat
Id | Title | Reference |

ABJX_v2_0 | SELECT | CPC 75(1993)339 |

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 [1]. | ||

Solution method: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 [2]. TRIATOM provides data necessary to drive ROTLEVD [3] and DIPOLE [4]. | ||

Restrictions: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. | ||

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:Highly case dependent. The sample data takes 17 sec for J=0 and 30 sec for J=1 (Coriolis decoupled) on the Convex C3840. | ||

References: | ||

[1] | B.T. Sutcliffe and J. Tennyson, Intern. J. Quantum Chem. 29(1991)183 | |

[2] | J. Tennyson, S. Miller, C.R. Le Sueur, this article, second program (SELECT). | |

[3] | J. Tennyson, S. Miller, C.R. Le Sueur, this article, third program (ROTLEVD) | |

[4] | J. Tennyson, S. Miller, C.R. Le Sueur, this article, fourth program (DIPOLE). |

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