Generate Displacements

Create subdirectories in the working directory, one for symmetric modes and one directory for each irreducible representation of the asymetric modes. Then copy input.dat, file11, geom.dat, and intco.dat (if appropriate) into each sub-directory.

Then modify the input.dat in each sub-directory according to the parameters below.

Modify default if in an asymmetric irrep:

default: (
symmetry = "The point group of the displaced geometry."
)

Modify input if in an asymetric irrep:

input: (

"Atoms, charges, and geometry must be altered according to the symmetry specified in default to specify all unique atoms in new point group."

Note: Atom numbering must remain consistent across all sub-directories; occasionally this is impossible. If so, atom numbering in file11 must be changed manually after gradients are obtained (change geometry and gradients).

Modify input.dat

psi: (
opt = false
disp = true
ndisp = 1
)

Add bmat: For each normal mode, displacements must be specified here. Stretching coordinates are displaced by 0.005 and bending coordinates by 0.01. A masses array must be added here as well. Symmetrical modes need both positive and negative displacements, while asymetrical modes only require one positive displacement.

bmat: (
 displacements = (
      ("mode number" (0.01 || 0.005))
  masses = ("Masses of each atom must be specified.")     
)

Note: When doing isotopic substitution, the displacements generated will be different because of the different masses array and consequently the intensities of those modes will change greatly according to the Eckart-Sayvitz conditions.

Finally, type bmat in each sub-directory. This will generate displacements for those modes and put them into geom.dat.

Also, type inputth in the irrep sub-directories to generate file30's for the lower symmetry displacements. Check to insure the atom numbering is consistent.