MOLCAS manual:

Subsections

• 6.17.1 MCKINLEY - Basic and Most Common Keywords

6.17 MCKINLEY — A Program for Integral Second Derivatives

MCKINLEY computes the analytic second derivatives of the one- and two-electron integrals with respect to the nuclear positions at the SCF and CASSCF level of theory. The differentiated integrals can be used by program MCLR to performs response calculations on single and multiconfigurational SCF wave functions. One of the basic uses of MCKINLEY and MCLR is to compute analytical hessians (vibrational frequencies, IR intensities, etc). Note that MCKINLEY for a normal frequency calculations will automatically start the MCLR module! For all other methods a numerical procedure is automatically invoked by MCKINLEY to compute the vibrational frequencies.

6.17.1 MCKINLEY - Basic and Most Common Keywords

Keyword	Meaning
PERTurbation	Suboptions Geometry (for geometry optimizations) or Hessian (full Hessian)