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Manuscript Title: VIDSIM: a Monte Carlo program for the simulation of atomic diffusion in diamond and zinc-blende structures.
Authors: U. Schmid, N.C. Myers, J.A. Van Vechten
Program title: VIDSIM VER. 2.11
Catalogue identifier: ABRF_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 58(1990)329
Programming language: C.
Computer: IBM AT.
Operating system: MS-DOS, UNIX (EXTENDED BSD 4.3).
RAM: 200K words
Keywords: Solid state physics, Diffusion, Semiconductor, Vacancies, Native and impurity Related point defects, Vacancy hopping, Frank-turnbull and kick Out mechanism.
Classification: 7.1.

Nature of problem:
Over the years various workers have proposed a large variety of models for point defect migration, interaction and reaction in semi-conductor crystals, and in other solids. There is much controversy over the validity of the several atom-level models that compete to be accepted as the explanation for macroscopic observations of atomic diffusion, etc. There are long standing disputes as to the true consequences of particular models and assumptions. We contend that the reason there is so much controversy in this field is that there has not been any widely available, practical, generally understood and accepted mechanism to establish clearly the relationship between the atomic level assumptions made in the various models and the macroscopic observables consequences that follow therefrom. Attempts at analytic solutions seem always to involve approximations, passages to limits, neglected processes, and impositions of boundary conditions. We have developed and are distributing VIDSIM to serve the function required to resolve these controversies. To accomplish this goal, it is evident that the user must be allowed to simulate virtually any model he wishes and to specify the parameters required by that model however he wishes. VIDSIM must then use an unbiased Monte Carlo algorithm to work out all thermodynamically allowed consequences of these assumption for a statistically significant sample over a statistically significant number of events. This must be done at reasonable cost and in reasonable time. Furthermore, to be effective, the program must be susceptible to use by typical experimental electrical engineers, metallurgists, and solid state physicists, who are not sophisticated in computer methods, and must run on widely available equipment, i.e. standard microcomputers.

Solution method:
Monte Carlo simulation. The program can be customized with a variety of parameters, which are to be given in special control files.

Running time:
Depending on the problem, from a few hours to several months on a microcomputer. It is expected that one uses one of the available MS-DOS multitasking programs on microcomputers so that the machine can be used for word processing, program development, etc. as desired during extended simulations. Intermediate results are permanently written on the hard disk. We find it optimal to examine the intermediate result of a long simulation once a day (using the multitasking program). This gives one time to think about what is happening and an opportunity to modify one's assumptions.