[Columbus] MCSCF in COLUMBUS

[Spiridoula Matsika]

Dear Hans and All,

Thank you all for your responses. As some of you suggested there are other ways to get the FCI energy. I have done that  using ciudg. As Scott just pointed out ciudg will also not work without an external space but I have constructed different kinds of CI expansions with a smaller active space and double excitations to virtuals. Since there are only 2 electrons in the system this still is a FCI calculation. And in FCI anyway I do the calculation  I get the same energies and gradients. BUT what I want to calculate is the derivative coupling and the breakdown into the CI and CSF part of the derivative coupling. And the CI part it turns out is not invariant to the orbitals even in FCI. I was shocked to see that but then I read more carefully the 2004 paper where the f was first implemented in Columbus (JCP 120, 7322) and it is explicitly stated there that this is the case. So a lot of you understand that much better than I do.

I have succeeded in running the CASSCF as FCI with gamess and gaussian. So I was wondering why it will not work in Columbus.

The output is below. As Ron guessed, the program runs the first CI iteration and then it stops. The energies are correct even at the first iteration.

Thanks,
Spiridoula

 

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> On Mar 2, 2017, at 8:21 AM, Hans Lischka <hans.lischka at univie.ac.at> wrote:
> 
> Dear Spiridoula,
> 
> In a FCI there are no orbitals to optimize since the energy is invariant under unitary transformations. The final reason of the breaking is the fact that there are no virtual orbitals, as you suspected. Actually, a simple energy calculation would be sufficient. I am not sure from the error message where the calculations really broke. Did it do so at the very beginning or did go beyond the energy calculation? Could yo send us the mcscfls file from the WORK directory?
> 
> The alternative is (as Felix wrote) to use the ciudg program and perform the FCI calculation with a corersponding reference space and zero excitations into the virtual (non-existent) space.
> 
> Ron and Thomas, do you have other suggestions?
> 
> Best regards, Hans
> 
> On 3/1/2017 8:46 PM, Spiridoula Matsika wrote:
>> Dear Columbus friends,
>> 
>> I am trying to run a benchmark calculation. The system is HeH+ and I am
>> setting up an MCSCF to act as FCI. So the active space contains all the
>> orbitals in the basis set. But the calculation always fails. I have
>> tried different versions of Columbus, different basis sets, etc. but
>> nothing seems to work. The error I get is:
>> 
>> *** error *** orthot: na,nb=         0         1
>> bummer (fatal):orthot: argument error                      0
>> 
>> 
>> Is there any reason that the MCSCF in COLUMBUS will not work if there
>> are no virtual orbitals and all orbitals are included in the CAS?
>> 
>> Thank you,
>> Spiridoula Matsika
>> 
>> 
>> 
>> Spiridoula Matsika
>> Professor of Chemistry
>> Department of  Chemistry
>> Temple University
>> 1901 N.13th Street
>> 242 Beury Hall
>> Philadelphia, PA 19122
>> 
>> Phone: 215 204 7703
>> Fax: 215 204 1532
>> smatsika at temple.edu <mailto:smatsika at temple.edu>
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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