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Manuscript Title: Vectorizing the Monte Carlo algorithm for lattice gauge theory calculations on the CDC CYBER 205.
Authors: D. Barkai, K.J.M. Moriarty
Program title: LATTICE
Catalogue identifier: AARH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 25(1982)57
Programming language: Fortran.
Computer: CDC CYBER 205.
Operating system: CYBER 200 O.S.
RAM: 256K words
Word size: 64
Keywords: Elementary, Particle physics, Qcd, Lattice gauge theory, Su(4) gauge theory, Su(n) gauge theory, Yang-mills theory, Non-abelian gauge theory, Non-perturbative effects, Phase transitions, Statistical mechanics, Action per plaquette, Monte carlo techniques, Vector processors.
Classification: 11.5.

Nature of problem:
The program calculates the average action per plaquette for SU(4) lattice gauge theory. Gauge theories on a lattice were originally proposed by Wilson and Polyakov for the regulation of the divergences of quantum field theory.

Solution method:
A Monte Carlo simulation of the system set up on a lattice (with varying numbers of sites per dimension considered) under an SU(4) gauge field generates a series of field configurations. The method of Metropolis et al. is used to achieve statistical equilibrium. Once in a state of statistical equilibrium any order parameter for the system can be measured. The vector capability of the CDC CYBER 205 is exploited to significantly reduce the time over that used on a scalar machine.

The storage required is dependent on the number n of dimensionsand the number l of lattice sites along each dimension. The arrays in the program that usually have the largest dimensions are dimensioned to nl**n (i.e. the number of links involved in the lattice). The execution time increases with the number of links and the number of Monte Carlo iterations. The code will only execute on CDC CYBER 200 computers due A to usage of extensions of FORTRAN which amount to syntax for vector operations.