Keywords for redundant internal coordinates in $redund_inp

With the parameters in $redund_inp the generation of redundant internal coordinates can be modified. All entries have to be made in the control file before invoking the ired option. Important options are:

• [iprint n]
  print parameter for debug output: The larger n is, the more output is printed n≥ 0, n≤ 5 (default: 0)
  
• [metric n]
  method for generating and processing of redundant internal coordinates
  n≥  - 3, n≤ 3, n ≠ 0 (default: 3)
  

  Values for the metric option:

  n = 1

  ``Delocalized Coordinates''
  The BmB^t matrix is diagonalized for the complete set of redundant internal coordinates, matrix m is a unit matrix.

  n = -3

  Delocalized Coordinates obtained with a modified matrix m, the values of m can be defined by user input (see below).

  n = -1

  ``Hybrid Coordinates''
  Natural internal coordinates are defined as in the old iaut option. If a cage remains, delocalized coordinates (as for n=1) are defined for the cage.

  n = -2

  Very simular to the n = 1 option, but for the remaining cage delocalized coordinates with modified matrix m are defined as for n = - 3.

  n = 2

  ``Decoupled coordinates''
  The redundant coordinates are divided into a sequence of blocks. These are expected to have decreasing average force constants, i.e. stretches, angle coordinates, torsions and ``weak'' coordinates. The BB^t matrix is diagonalized for each block separately after the columns of B were orthogonalized against the columns of B of the the preceding blocks.

  n = 3

  ``Generalized natural coordinates''
  Natural internal coordinates are defined first, for the remaining cage decoupled coordinates are defined.

• [type r]
  a positive real number, which is an approximate ``force constant'', can be read in for each type of coordinate (see below). The force constants are used for the definition of the matrix m in BmB^t.