Description

This tells AMPAC that symmetry data defining the constraints on related bond lengths, angles and dihedrals has been defined by the user. This data section is located after the geometry section and is initiated by the string

$$ symmetry - constraints

which can be abbreviated as

$$ symm

Each symmetry definition is given on a separate line. A more complete discussion of symmetry including the data file structure and the symmetry functions themselves can be found in Chapter 5, Presenting Input to the Program. It is now possible to utilize symmetry constraints with Cartesian coordinates as well as internal geometry definition systems.

Examples:

  am1 rhf singlet t=1h truste symmetry grad bonds=all
WATER WITH TWO PARTIAL CHARGED SPARKLES
SPARKLES w/PARTIAL CHARGES, Na and Cl, T W/ HOURS
 O              0.000000  0    0.000000  0    0.000000  0    0    0    0
 +              1.000000  0    0.000000  0    0.000000  0    1    0    0   0.50
 H              1.000000  1  128.300000  1    0.000000  0    1    2    0
 H              1.000000  1  128.300000  1  180.000000  0    1    2    3
 -              2.000000  0  128.300000  0  180.000000  0    1    3    4  -0.50
 0              0.000000  0    0.000000  0    0.000000  0    0    0    0
$$ symmetry - constraints
  3, 1, 4,       
  3, 2, 4, 5,
$$ end of extra data