Author Topic: Structure Optimization employing rijk (HF) and rimp2  (Read 9727 times)

Stefan

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Structure Optimization employing rijk (HF) and rimp2
« on: October 08, 2007, 01:37:53 pm »
Hello,

I want to optimize a structure employing the rijk-approximation for the HF-part as well as the rimp2 approach. Employing jobex does not work. I receive the following error message:
Quote
Program dscf can not use the RI-J approximation.
Please either use the ridft program or delete the option $rij
from your control file.
I used the following command to start the calculation:
Quote
nohup jobex -level mp2 -ri -c 5 -gcart 4 &
The following seems to work:
1. starting ridft
2. starting rimp2
3. starting relax
4. restart with 1.
Which flag must be used to employ the jobex script?

Regards, Sefan




 

uwe

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #1 on: October 08, 2007, 04:19:58 pm »
Hi,

unfortunately jobex is not able to differ the RI of RI-MP2 from the RI of RI-DFT (which is RI-J).

That is a bit unfortunate, but quite easy to circumvent:

Code: [Select]
export dscf=ridft
jobex -ri -level mp2 [...]
unset dscf

should work.

The unset dscf line is necessary to avoid problems with non-RI-MP2 calculations in the same shell after the job, since a usual Hartree-Fock geometry optimization would also use ridft instead of dscf otherwise.

The same trick can also be used for RI-CC2 or RI-MP2 calculations with the ricc2 program (jobex -level cc2) together with RI-JK.

Regards,

Uwe

Stefan

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #2 on: October 09, 2007, 02:26:30 am »
Thank you.

Regards, Stefan

Arnim

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #3 on: October 16, 2007, 10:21:55 am »
Hi,

here is a little outlook for this problem.

In the next version it will be possible to perfom RI-SCF based geometry optimizations 
with the jobex-script, routinely. Using the rijk-approximation for the HF-part and the CPHF-part
in MP2 or CC2 gradient calculations. The ridft and ricc2 programs will be used and everything
can be prepared in define.

Regards,
Arnim

christof.haettig

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #4 on: October 17, 2007, 05:39:48 pm »
Hi,

the optimization 'by hand'  or the trick described by Uwe are work arounds for the time being, but note:
The gradients which rimp2 and/or ricc2 compute will in that case be those for conventional (i.e. non-RI) SCF+
RI-MP2 energy and do not fit 100% to the computed total energy. Probably in most cases, this will not be
a serious problem, but you should be aware that you can't use tight convergence threshold for jobex in that
case.
           Christof

Stefan

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #5 on: October 19, 2007, 03:45:37 pm »
Thank you for the further informations.

Regards, Stefan

christof.haettig

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Re: Structure Optimization employing rijk (HF) and rimp2
« Reply #6 on: September 25, 2015, 07:42:50 pm »
The above discussion is outdated since several years.

To optimize geometries at the RIJK-HG + RI-MP2 (or RI-CC2) level use the following command:
       jobex -level cc2 -rijk