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Manuscript Title: Computer simulation of correlated self-diffusion via randomly migrating vacancies in cubic crystals.
Authors: D. Wolf, K. Differt
Program title: RANDOM VACANCY MIGRATION
Catalogue identifier: ACKO_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 13(1977)167
Programming language: Fortran.
Computer: CDC 6600.
Operating system: SCOPE 3.4.
RAM: 58K words
Word size: 60
Keywords: Solid state physics, Crystal lattice, Vacancy, Correlated Self-diffusion, Random migration, Fcc, Bcc, Simple cubic, Nmr, Computer simulation, Monte carlo method, Correlation factor.
Classification: 7.1.

Revision history:
Type Tit le Reference
adaptation 0001 CORRELATION FACTOR AND NMR See below

Nature of problem:
Computer simulation of the relative jumps of atoms induced by a randomly migrating single or double vacancy in a face-centered cubic, body-centered cubic, or simple cubic crystal lattice.

Solution method:
The random vacancy jumps are simulated using a procedure for the creation of a sequence of random numbers (Monte Carlo method).

Restrictions:
The number of atoms the relative motions of which may be studied is limited by the lengths of the required arrays (see section 3.3 of the long write-up).

Unusual features:
The program as it stands is used for NMR studies of self-diffusion (see next paper in this issue). But, with few changes it may be used for simulating very common diffusion problems, including annealing of vacancies at different kinds of sinks.

Running time:
About 50 sec for the simulation of the diffusion via mono-vacancies in a bcc lattice. The running time is proportional to the product of the number of jumps in each encounter with the number of encounters.

ADAPTATION SUMMARY
Manuscript Title: Determination of correlation factor and NMR diffusion parameters from the computer-simulated random motion of vacancies in cubic crystals.
Authors: D. Wolf, K. Differt, H. Mehrer
Program title: 0001 CORRELATION FACTOR AND NMR
Catalogue identifier: ACKO_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 13(1977)183
Programming language: Fortran.
Classification: 7.1.

Nature of problem:
Combined with the program presented in the preceding paper this program may be used for calculating (i) the geometrical correlation factor associated with the correlated movements of individual atoms for vacancy-induced self-diffusion in cubic crystals, as well as (ii) the basic quantities associated with the interpretation of NMR studies of self diffusion, such as the correlated relative geometrical displacements of any two atoms, and their total number of relative jumps in encounters with mono- or divacancies in cubic crystals.

Solution method:
Simple sums over displacement probabilities of atoms, which are calulated by the program discussed in the preceding paper.

Restrictions:
Only sc, bcc, and fcc crystal structures for monovacancy diffusion, and bcc and fcc lattice structures for self diffusion via divacancies are considered.

Running time:
As an example, the test run simulates self diffusion via mono-vacancies in a bcc lattice. Approximately 9 sec are required for compilation and 53 sec for execution. The running time depends strongly on the values