Calculation of Fragment Geometry

The program is able to calculate a wide variety of internal coordinates for each fragment located in the search procedure. The subset of parameters required for a particular study is entirely under the control of the user. Each individual parameter is specified in terms of the (user-defined) atomic enumeration of the fragment. Three major commands, DEFine, SETup and TRAnsform are used to specify geometrical parameters. 

The TRAnsform command is used to perform unitary and binary operations on parameter(s) established using SETup/DEFine. A set of FORTRAN-like operators, e.g. SIN, COS, ABS, +,, etc., are provided which, when used in successive 

TRAnsform statements, enable the user to construct linear combinations of the initial parameters. For example, we may use TRAnsform to obtain the mean valence angle at nitrogen, from the individual valence angles obtained using DEFine, for use, perhaps, as a single-parameter measure of pyramidality. 

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