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of the hour:
Reinhard Maurer
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OS: Windows
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Geometrically Restrained INorganic Structure Prediction
GRINSP is a Monte Carlo code (FORTRAN) for the prediction of
inorganic crystal structures built up from defined polyhedra.
The main purpose of GRINSP is to generate hypothetical inorganic structures MxM'yXz which will be documented in a searchable database : PCOD (Predicted Crystallography Open Database), a subset of the COD.
GRINSP does not work by applying simulated annealing to a starting random configuration. Version 2.00 works schematically as follows, by using the Monte Carlo method :
Manual selection of the constraints on cell parameters, of restrained interatomic distances, of the type(s) of coordinations, and of the space groups. Then the Monte Carlo process starts.
Random selection of the cell parameters inside of the predefined range.
Random positioning of a first cation M (or M') of the future MxXy (or MxM'yXz) compound on a general or special position, itself selected randomly.
Random positioning of the next cations (random choice of M or M') in respect of the distance restraints with the atoms already accepted, on a general or special position, itself selected randomly.
If a model fulfills all distance and coordination criteria, place the X atoms at M-M midpoints, refine the atomic positions and cell parameters so as to improve an R factor.
Continue to try to predict structures in that way till a certain number of cells are tested.
Find if the predicted structures are new or were already described (using CS - Coordination Sequences), keep those with best R factors.
http://www.cristal.org/grinsp/
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