How to do PES of a specific singlet excited state

How To
#1

Hi, I’m a new Q-Chem user and would like to perform PES scan of the first singlet excited state. Here is my input file:

$molecule
xxx
$end

$rem
   BASIS  =  def2-svp
   CIS_N_ROOTS  =  3
   CIS_STATE_DERIVATIVE  =  1
   CIS_TRIPLETS  =  0
   EXCHANGE  =  omegaB97X-D
   GUI  =  2
   JOB_TYPE  =  PES_Scan
   SCF_MAX_CYCLES  =  100
   SOLVENT_METHOD  =  SMD
$end

$scan
tors  9  8  11  21  90.0  0.0  -10.0
$end

$smx
   SOLVENT  acetonitrile
$end

However, there is an error message says “PES scan currently implemented only for the ground state. Please remove CIS_STATE_DERIV from $rem.”
I understand that the answer is straightforward like what the error suggested. But is there anyway I can do it?

Thank you very much

#2

JOBTYPE = PES_SCAN is not implemented for excited states.

You could implement something similar yourself, at the level of the input file, by using the CONSTRAINT subsection of $opt in an excited-state geometry optimization. You would need to step along the relevant torsion angle in increments, with each one as a separate Q-Chem job.

#3

Dear Prof. Herbert,

Thank you very much for your suggestion.