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12.5.6 Evaluate Degree of Freedom

The evaluate degree of freedom evaluates the conformation generated up to this point in the search. N.B., the evaluate degree of freedom is specified using the EVL keyword. The letter, A is intentionally omitted. In addition, it has the capability of running any energy commands from the main program. These degrees of freedom keep running totals of the minimum and maximum values found, and they are printed at the end of normal execution. In addition, the evaluations are saved for writing to the conformation file if a WRITE degree of freedom follows the evaluation. If no options for this degree of freedom are specified, then the energy is used.

If the CAVITY option for the GEPOL molecular surface code is set, see Gepol Command, and if energies are being evaluated, then a cavity formation energy will be added to the energy evaluation. This cavity formation energy calculation is currently quite expensive.

The MINI evaluation option call the energy minimization and dynamics command (see Energy Manipulations). Prior to call this option, CONGEN saves the coordinates of the generated coordinates and will reset them when the degree of freedom passes control to the previous degree of freedom. Any modifications to the coordinates are passed to the next degree of freedom. In addition, the coordinates of the surrounding atoms are fixed, (see Fixed Atoms).

The RMS evaluation option computes the RMS difference between the current coordinates and the coordinates when the CONGEN command was invoked.

The RANDOM evaluation option assigns a random number as the evaluation of this conformer. In conjunction with the CUT, MINCUT, MAXCUT, and FILTER options below, it can be used to select a number of conformers at random for succeeding constructions.

The USER evaluation option calls the user defined evaluation. This option is not well developed, see the source code files cgen.c and usersb.flx for more information.

The NPRINT option is used to limit evaluation listings to every NPRINTth evaluation. If NPRINT is set to zero, then all evaluations are listed. At present, NPRINT does not turn off the output of ECNTRL when a minimization is done on the conformations.

The three cutoff options; CUT, MINCUT MAXCUT; are used to limit the number of conformations written to the file. See Write Degree of Freedom for a description of how these options work to limit energy outputs into the log file.

The FILTER option is used in conjunction with cutoff options to stop conformers for being passed down to succeeding degrees of freedom. When the FILTER option is absent, then all conformers pass to succeeding levels. When the FILTER option is present, then only those conformers which are printed are passed to the next degree of freedom.

NPRINT and the cutoff interact as follows: The NPRINT check is made first. If the conformation's energy is to be printed, the cutoff check is then made.