Parameter optimization involves using data-bases or sets of reference data. These sets can be large, the largest, NORMAL, contains over 8,000 individual files. To make working with these files easier, several utilities have been written. These are:
AND selects all compounds that contain one or more of a user-specified set of elements. Other elements can also be present. Thus if AND was used with the element Ti, then all species in the database that contain one or more atoms of titanium would be selected.
ONLY selects all compounds that contain one or more of a user-specified set of elements, but no other elements Thus if ONLY was used with the elements H C N O, then all species in the database that contain one or more atoms of hydrogen, carbon, nitrogen or oxygen would be selected. This would include glycine and TNT, but exclude chloroform (Cl would cause CHCl3 to be excluded.)
NOT selects all compounds that do not contain any of a user-specified set of elements. NOT with C would exclude all organic compounds.
ALL selects everything.
FILES generates a list of data sets in order of increasing atomic number. FILES is run in the folder that contains the data-base
MERGE combines the results of surveys of different methods. For a given data-set, surveys could be run using MNDO, AM1, PM3, PM6, etc, and the results merged into a set of HTML tables. One table would be for heats of formation, one for dipoles, etc.
SELECT is a utility for selecting a sub-set of data files from a data-base. SELECT uses a single argument, either 'AND', 'ONLY', 'NOT', or 'ALL.' Because SELECT is designed to be used with an argument, each of the four possible arguments is represented by a utility. SELECT is not normally used on its own, it is usually used embedded in the appropriate utility.
STATISTICS analyzes the output of a PARAM survey and generates statistics on the errors.
STATS calls STATISTICS and MERGE