In Q-CHEM,whether Frozen Atoms or Potential Energy Surfaces use at the same time is possible?
I assume by “Potential Energy Surfaces”, you mean JOBTYPE = PES_SCAN (potential energy scan). In that case, this appears to be incompatible with fixed-atom constraints.
With JOBTYPE=PES_SCAN and
$scan stre 1 2 1.0 2.0 0.5 FIXED 1 XYZ $end
Q-Chem returns a sensible error message:
Invalid constraint for potential energy scan