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Manuscript Title: A program for the study of short range order of binary alloys.
Authors: G.L. Bleris, Ch. Polatoglou
Program title: SROCASE
Catalogue identifier: ACKN_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 13(1977)49
Programming language: Fortran.
Computer: UNIVAC 1106.
Operating system: EXEC8.
RAM: 9K words
Word size: 36
Keywords: Solid state physics, Crystal lattice, Fcc, Binary alloy, Newton-rapshon method, Vacancy, Cowley-warren parameter, Pvm, Cluster, Diffraction pattern, Diffuse intensity Profile, Experiment.
Classification: 7.1, 7.4.

Nature of problem:
The program SROCASE was developed to calculate the mean distribution of vacancies in an fcc lattice using data related to the diffuse scattered intensity in diffraction patterns and to reconstruct the patterns. Thus from the diffraction data the Cowley-Warren s.r.o. parameters are estimated and the clusters that satisfy these coefficients are obtained by theprobability variation method (PVM).

Solution method:
To determine the s.r.o. coefficients ai a Monte Carlo integration was performed over a domain D defined in such a manner that at a point x Epsilon D the integrand function has a value given by the diffraction data. The PVM requires the solution of a set of simultaneous nonlinear equations by the Newton-Raphson method. Application of this method leads to the solution of a system of linear equations by the Gauss method.

The determinant of the simultaneous linear equations must be different from zero.

Unusual features:
By modifying FUNCTION DOMAIN other diffuse intensity data may be reproduced.

Running time:
The time to calculate the first 8 s.r.o. parameters and the maximum probability and to print a diffuse intensity profile is 232 sec. The time for each additional diffuse intensity profile is 84 sec.