Derivative File Screening Program
This program is used to find out which atoms are least satisfied with their current parameters, with respect to a particular module. It reads the derivative file produced by the module of interest, finds the largest derivatives for the three classes of parameters; XYZ, B, and OCC, and writes a nicely formatted list of them. It is intended that this list be used to aid in the interpretation of the map when work is being done to manually rebuild a model.
The refinement of a model has converged when none of the parameters are changing. However, a parameter can become fixed for two reasons; either all the modules agree that this is a good value, or each module prefers a different value and the parameter is balanced in between. The second case is a sign that manual intervention is required to place the atoms in that region in a new local minimum. This program is a tool for finding which regions of the model are in trouble. Where the various modules are at odds, the derivatives from each module will be larger than normal and point in opposite directions. This utility will read the derivative file and point out the problem areas in the model.
The program requires that the coordinates of the model, and the derivative file be entered before the SCREEN command. A CELL and a GRID statement may be required if the fraction or grid coordinate system is used for either the coordinates or the derivatives.