1. You need to define runtyp=conical

2. From one of my inputs: 

$DET NCORE=26 NELS=11 NACT=11 NSTATE=5 WSTATE(1)=1,1,0,0,0 $END

$MCSCF MAXIT=5000 cistep=aldet fors=.t. soscf=.t. $end

$CONICL opttyp=gpwnac ixroot(1)=1,2 $end

3. keep in mind, that if you have symmetrical system and intersection of states, which correspond to different irreps, you can take it into account and largely reduce computational effort

Thank You, Oleg Gromov . I want to know how to locate the crossing point (intersection) by looking at the log file as well,

Thank You.

It is just like any other optimization- calculation stops as soon as CI is achieved.

Thank you again, I want to know how to prepare the $DATA part as well . Is it correct to include the output of the AIMPAC keyword used in TDDFT calculations in gamess..? Since I want to check the intersection of a photochromic compound for the ring open to close process.

Thank you.

Had a look at your out file, turned out, that you are working with Firefly (note, it is NOT GAMESS), unfortunately, I did not try it, so have nothing to advice (and a part of input I gave is related to GAMESS US, not Firefly). Try to ask a question at firefly forum. Sorry for that.

OK then I will have a look . Thank you again .

It is just an example I want to know how to locate the conical intersection using GAMESS only I really appreciate if you can send me a sample calculation related to .

Thank You

I think the following link can be useful for you:

http://classic.chem.msu.su/gran/gamess/Locating_Conical_Intersections_and_Interstate_Crossings_with_Firefly.html

Thank you Anton ,