GPOP reference manual

introt calculates reduced moments of inertia and rotational constants for multiple intramolecular rotations. It reads a text file, basename.inp and prints output to standard output. It is essentially same as gpop6mrt except that it does not require a GPOP format file and can be used with a text input file with minimal information for the calculation.

See the manual for gpop6mrt for the input and output except for the differences described below.

The program expects a file, basename.inp, containing the following information.

Geometry specification

Following is an example geometry specification.

nAtms 10
geom{
  6 0 0.011808 0.533737 0.000000
  1 0 -0.248691 1.589988 0.000000
  6 0 0.011808 -0.197313 1.301544
  6 0 0.011808 -0.197313 -1.301544
  1 0 -0.975580 -0.638162 1.534296
  1 0 0.724590 -1.034050 1.294237
  1 0 0.269064 0.459888 2.140199
  1 0 -0.975580 -0.638162 -1.534296
  1 0 0.724590 -1.034050 -1.294237
  1 0 0.269064 0.459888 -2.140199
}geom

The input must start with the number of atoms nAtms and should be followed by the cartesian coordinate input section geom. Each atom is specified by (1) the atomic number, (2) atomic type (not used, but exist for the consistency with Gaussian output), and (3)-(5) x-z coordinates in Angstrom.

As one special function which cannot be performed with gpop6mrt is that this program accepts geometry input with dummy atoms, simply setting the atomic number to be 0. The dummy atoms, thus specified, can be used to specify some special internal rotor which rotates around an axis not passing through any of the atoms in the molecule.

Internal Rotor Specification

This part is exactly the same as those in .mrt input for gpop6mrt.

1:3-5-6-7
1:4-8-9-10

The output is also essentially same as gpop6mrt except that no analysis was made for the quantities that requires vibrational frequency analysis.