Q. PES and Vibrational frequency calculations

 

A. In the present version of the SAC-CI method, the harmonic frequency can be calculated in combination with the GSUM method. An example is given as test689.com. In the GSUM step, the sample geometry should include the stationary point.

  GSUM method is very important for calculating potential energy curves. Please refer to SAC-CI Guide for details and test644 which calculates the potential energy curves of Li₂. For calculating reliable harmonic frequency and anharmonic frequency, the GSUM method is strongly recommended.