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Igor Polyakov
polyakoviv@gmail.com

i didn't check your files but i wanted to give some general comment- in any MCSCF calculation with "not proper" orbital selection the results should be very obscure. The general rule is to include "important" orbitals in active space, for example if u study s0-s1 homo-lumo transition u must include these right homo and lumo orbitals, but in general these orbitals are not homo and lumo orbitals of RHF printout- you should conduct CIS calculations or inspect your orbitals manually. In general case of some reaction i suppose u could try to include high-lying occupied orbitals and low-lying vacant orbitals which concern the chemical bond to be broken or made during the reaction.

Best luck. Igor.


On Wed Aug 19 '09 4:33pm, Alex Maiorov wrote
--------------------------------------------
>Hallo,

>This i have read in the previous discussion about SA and SS MCSCF
>>>>>The proper selection of active space is very important.
>>>>>CAS (2,2) is natural for your problem. You can use larger spaces
>>>>>but be careful to select proper orbitals!
>>>>>And sure, you can use $guess norder=1 iorder(1)=... to reorder orbitals.

>i cant understand how to find out which orbitals are proper or not!
>How can i see what to reorder? What`s the metter with my results if i didnot select the proper
>orbitals?

>For example
>I made calculations of Transition state of reaction O3+C2H4 in basis 6-311pg**:

>1)by the means of ss cas(8,8) - name of file           d_c2h4o3_cas.inp
>2)i calculated the caspt2 energy - name of file        d_c2h4o3_cas_pt2.inp

>Don`t pay attention than files were made for GAMES US, i made this calculation
>in pcgamess too, but i could not find them.

>Thank you very much/