geom(1)                                                                                                                                    geom(1)

NAME

       geom - analyzes a molecular geometry input in Cartesian coordinates.

DESCRIPTION

       The  program  geom  reads a set of Cartesian coordinates and determines from them the bond distances (Bohr and angstrom), bond angles, tor-
       sional angles, out-of-plane angles (optional), moments of inertia, and rotational constants.

FILES REQUIRED

           input.dat          - Input file
       and one of the following:
           geom.dat           - geometry file
           file11.dat         - PSI-format geometry/gradient file

FILES GENERATED

           geom.out           - file containing the analysis

INPUT OPTIONS

       The geom program has the following options:

       -h     Print help information (these options).

       -aces [filename]
              Read the input in an ACES output format, with each line consisting of atomic symbol, atomic number, and  Cartesian  coordinates  (in
              Bohr).  The optional argument is the name of the geometry input file, which defaults to geom.dat.

       -qchem [filename]
              Read the input in an QCHEM output format, with each line consisting of the atom number, the atomic symbol, and Cartesian coordinates
              (in Angstroms).  The optional argument is the name of the geometry input file, which defaults to geom.dat.

       -xyz [filename]
              Read the input in an XYZ output format.  The first line contains the number of atoms and the second line is a comment line.   Subse-
              quent lines each contain the atomic symbol and Cartesian X Y and Z coordinates (in Angstroms).  The optional argument is the name of
              the geometry input file, which defaults to geom.dat.

       -oop   Print out-of-plane angles, where the angle a-b-c-d is defined as the angle formed by the vector a-d and the plane defined  by  atoms
              b, c, and d.

       DO_OOP = boolean
              Same as command-line switch -oop described above.

       ISOTOPES = matrix of reals/strings
              Used to specify masses to be used in the calculation of the center of mass and rotational constants.  One array is provided for each
              isotopomer to be calculated.  The arrays can mix floating point numbers with strings which designate isotopes.  If this array is not
              given  and  file11.dat  is  present, then the masses will be obtained by converting the atomic numbers in file11.  If masses are not
              given by ISOTOPES or by file11, then no mass-related quantities will be calculated.

       -g [filename]
              Read Cartesian coordinates from a file other than file11.dat.  If a filename is not given, the default is geom.dat.  The alternative
              file is assumed to be in a format similar to that of PSI's geom.dat.  Since such files do not contain atomic numbers, the moments of
              inertia and rotational constants are not calculated if this option is used.

       READ_GEOM = boolean
              This option in input.dat tells geom to read the geometry from geom.dat in the PSI geom.dat format.

       -a     Print parameters for all pair distances.

       PRINT_ALL_DIST = boolean
              Same as -a flag described above.

       -d distance
              Only print parameters involving pairs of atoms which are less than distance bohr apart (default value is 4.0 bohr).

       PRINT_DISTANCE = value
              Same as -d flag described above.

       -angstrom
              The input coordinates are in angstroms, not bohr.

       ANGSTROM = boolean
              If TRUE, the input coordinates are in angstroms instead of bohr.  The default is FALSE.

              The following example is for calculating the geometrical information for water with several different  isotopes.   The  geometry  is
              read from geom.dat rather than from file11.dat.

              geom: (
                 read_geom = true
                 isotopes = (
                    (O H H)
                    (O D D)
                    (O18 1.007825 1.007825)
                  ) )

                                                                   5 June, 1998                                                            geom(1)