A procedure compatible with X-PLOR for the calculation of electron-density maps weighted using an R-free-likelihood approach

A program has been developed that uses an R-free-likelihood-based technique to estimate the errors of phases calculated from atomic models. This technique allows one to obtain realistic estimates when it is applied to refined models. The program reads a file of structure factors in the X-PLOR format and creates a new one that contains information necessary to calculate weighted maps. The output file can be used directly by X-PLOR.