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Manuscript Title: A vectorized code for the Monte Carlo computation of spin-dependent static potentials in QCD.
Authors: M. Campostrini, K.J.M. Moriarty, C. Rebbi
Program title: SPINSU3
Catalogue identifier: AALH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 42(1986)175
Programming language: Fortran.
Computer: CDC CYBER 205, MODEL 682.
Operating system: CDC CYBER 200 VSOS 2.1.6.
RAM: 1600K words
Word size: 64
Keywords: Particle physics, Elementary, Quantum chromodynamics, Lattice guage theory, Su(3) gauge theory, Spin-dependent forces, Monte carlo techniques, Vector processor.
Classification: 11.5.

Nature of problem:
Spin-dependent forces between heavy quarks can be expressed in terms of vacuum expectation values of color electric and magnetic fields in the presence of a Wilson loop; their Monte Carlo computation requires the measurement of Wilson loops with two plaquette insertions on 'vertical' sides.

Solution method:
SU(3) gauge theory is simulated with a standard Monte Carlo technique, using the methods illustrated (Comp. Phys. Commun. 32(1984)1) to optimize the computation on a CDC CYBER 205. Loop measurements are performed efficiently by transforming the configuration into the temporal gauge; horizontal sides of every loop are computed with the "multi-hit" technique, to improve statistics.

(a) Space lattice size NS must be even.
(b) Fast memory requirements are: 55*LS*NS**3 words for version I, 30*LS**2*NS**3 words for version II, both with half-word precision arithmetic (LS = maximum separation of static quarks).
(c) Temporary mass storage requirements are: 0.55*NS**3*NT (512 word) blocks for both versions (NT = temporal lattice size).

Running time:
One iteration (20 upgradings + 1 measurement) takes 1600 CPU seconds on a two pipe CYBER 205, for a 16**3*32 lattice and half-precision arithmetic.