The second derivatives with respect to Cartesian displacements (3 translations) of the free atoms (atoms not belonging to any block) and those with respect to block motions (3 block translation/3 block rotations) are calculated by numerical differentiation of the gradient. The accuracy of the second derivatives is mainly influenced by the accuracy of the gradient evaluation (e.g. accuracy numerical integration) and the step size in the numerical differentiation. The parameters DISRAD and DISANG can be specified to set the step size for Cartesian displacements (translations) and block rotations respectively. The step size for angles is automatically scaled with the block size.
FREQUENCIES {DISRAD=drad} {DISANG=dang}
The default values for drad and dang are the same as in the case of a standard numerical frequency run.
