PC GAMESS/Firefly-related discussion club

Learn how to ask questions correctly

Andrei V Scherbinin
scherb@classic.chem.msu.su

>I am a long time Gaussian user who is new to PC GAMESS.  As such, I have been performing a few basic calculations in order to familiarize myself with the program.  I have run into a problem while trying to optimize the geometry of a simple molecule in an excited state.  Specifically, I cannot determine the how to tell the program to optimize the geometry while the molecule is in the excited state.  All of my efforts thus far simply yield the ground state energy and geometry.  For simplicity, I have been using CIS to generate the excited states.  My feeling is that there is some simple nuance I am missing that needs to be placed in the input file.  I should also mention I am aware of the information that is punched into the .dat file of the program pertaining to certain properties of the excited state.  However, I’m not sure if it is necessary to read this information back into a new input file to relax the excited state geometry.  Thanks for the help.
>


In order to optimize the excited state geometry, you first of all need the gradient
calculated for this particular state. To require calculation of a specific state
gradient/properties using CIS, just put the following information into the $CIS group:  

$CIS NSTATE=3 ISTATE=3 $END

NSTATE is the total number of excited states to be found, ISTATE is the target excited
state number.


(see readme.cis for further details)