Q. Potential curve for single-bond twisting.

 

A. Twisting single-bonds sometimes induce large change in the amplitude of the canonical MOs. In such situations, one to one correspondence between MOs in the neighboring geometry become worse and this affects the accuracy of the GSUM calculations.

  We recommend using LMO in the GSUM calculation for the twisting single-bond, because LMO is much more independent on the geometry of the molecules.