FraGen: A computer program for real-space structure solution of extended inorganic frameworks

The FraGen (framework generator) program has been developed for real-space structure solution. It has been designed especially for the generation of extended inorganic frameworks in a given unit cell. FraGen is based on the parallel tempering global optimization method. Various restraints can be introduced into FraGen, such as restraints on bonding geometry, relative reflection intensities and three-dimensional density maps. The basic inputs for FraGen are the space group and cell parameters. The number of unique atoms is not a necessary input, since it can be estimated from certain constraints. FraGen also has the ability to exit unpromising simulation cycles to save computation time for promising ones. Program features, methods and three examples are demonstrated. The FraGen program for the Windows platform is available from the authors upon request.