INTDER

intder performs simple-/symmetry-internal coordinate transformations for geometry displacements and derivatives. This is a port of the original Fortran INTDER program by Wesley D. Allen and coworkers.

Input

The input format is compatible with the original Fortran version, but whitespace is much less significant. Fields just need to be separated by some number of tabs or spaces.

Displacements

A simple input file for converting 4 SIC displacements for water looks like:

# INTDER ##########################
    3    3    3    0    0    3    0    0    0    1    0    0    0    1    1    0
   14
STRE     1    2
STRE     2    3
BEND     1    2    3
    1   1   1.000000000   2   1.000000000
    2   3   1.000000000
    3   1   1.000000000   2  -1.000000000
    0
      0.000000000000     1.431390244079     0.986041163966
      0.000000000000     0.000000000000    -0.124238450265
      0.000000000000    -1.431390244079     0.986041163966
DISP   4
    1       0.0050000000
    0
    2       0.0050000000
    0
    3       0.0050000000
    0
    1      -0.0050000000
    2      -0.0050000000
    3      -0.0100000000
    0

Force Constants

An input file for converting force constants from SICs to Cartesian coordinates, again for water, looks like:

# INTDER ##########################
    3    3    3    4    0    3    2    0    0    1    3    0    0    0    0    0
   14
STRE     1    2
STRE     2    3
BEND     1    2    3
    1   1   1.000000000   2   1.000000000
    2   3   1.000000000
    3   1   1.000000000   2  -1.000000000
    0
        0.0000000000        1.4313273344        0.9860352735
        0.0000000000        0.0000000000       -0.1242266321
        0.0000000000       -1.4313273344        0.9860352735
         H1          O16          H1
    1    1    0    0      8.360863692425
    2    1    0    0      0.364250381719
    2    2    0    0      0.705590041836
    3    3    0    0      8.562725561924
    0
    1    1    1    0    -41.638868371821
    2    1    1    0     -0.611029974345
    2    2    1    0     -0.447356783193
    2    2    2    0     -0.701565547377
    3    3    1    0    -41.484904978222
    3    3    2    0      0.392943158463
    0
    1    1    1    1    181.917347386091
    2    1    1    1     -0.292134838642
    2    2    1    1      0.372522604963
    2    2    2    1      1.034069182728
    2    2    2    2     -0.655831802100
    3    3    1    1    182.206178030730
    3    3    2    1     -1.233550191665
    3    3    2    2     -0.820459303061
    3    3    3    3    183.621273961541
    0

References

• D. F. McIntosh, K. H. Michaelian, and M. R. Peterson. Can. J. Chem. Vol. 56, 1978
• E. B. Wilson, Jr., J. C. Decius, and P. C. Cross. Molecular Vibrations, 1955.
• W. D. Allen and A. G. Csaszar. J. Chem. Phys. 98, 1993.
• A. L. L. East, W. D. Allen, and S. J. Klippenstein. J. Chem. Phys. 102, 1995