I try to calculate the energy with multireference configuration interaction method of certain system using gaussian 09 packet, but I do not know what is the keyword.
Hi Antonio,
you can use the keyword CASSCF(N,M), where N is the number of electrons in the active space used by this method and M is the number of orbitals in the active space, http://www.gaussian.com/g_tech/g_ur/k_casscf.htm
Best regards,
Aleksey.
@Aleksey E. Kuznetsov CASSCF is not multireference configuration interaction. CASSCF can be used for building references.
As far as I know Gaussian don't have MRCI and you should use Molpro or GAMESS or ...
http://en.wikipedia.org/wiki/Multi-configurational_self-consistent_field
Yeah Its right, This is the demerits of Gaussian09. For efficient MRCI calculation i think MOLCAS, MOLPRO are best. But this are not freely available. ORCA, GAMESS, FIREFLY are free and have this capability.
COLUMBUS does MRCI, and it is also free. https://www.univie.ac.at/columbus/
@Ron Shepard COLUMBUS have any default input facility for different atoms?.
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