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Manuscript Title: DUMBELL: a program to calculate the structure and thermodynamics of a classical fluid of hard, homonuclear diatomic molecules.
Authors: F. Lado
Program title: DUMBELL
Catalogue identifier: AADS_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 39(1986)133
Programming language: Fortran.
Computer: IBM 3081.
Operating system: MVS.
RAM: 140K words
Word size: 32
Keywords: Fluid dynamics, Solid state physics, Other, Molecular fluids, Percus-yevick analytic Model, Ornstein-zernike Equation.
Classification: 7.7, 12.

Nature of problem:
Calculation of the spherical harmonic coefficients of the pair distribution, direct correlation, and other functions of a fluid of hard, homonuclear diatomic molecules and from these its thermodynamics.

Solution method:
Spherical harmonic coefficients of the molecular direct correlation function C(12) are obtained from an ad hoc but surprisingly effective generalization of the Percus-Yevick hard sphere solution. These are Fourier transformed to yield, through the Ornstein-Zernike equation, the transform of the series function S(12). After inverse Fourier transformation of these, the function S(12) is reconstructed from its coefficients and used finally to generate the spherical harmonic coefficients of the pair distribution function g(12) in Percus-Yevick approximation.

Up to 14 coefficients can be used in the spherical harmonic expansions.

Running time:
The test job, using five harmonic coefficients, takes 81s on an IBM 3081; with 14 coefficients, the running time is 130s.