i-PI and ORCA cllient

Gábor Magyarfalvi

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Mar 27, 2020, 9:22:07 AM3/27/20

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We are trying to work on a problem similar to:

Elucidating the Nuclear Quantum Dynamics of Intramolecular Double Hydrogen Transfer in Porphycene

Yair Litman, Jeremy O. Richardson, Takashi Kumagai, and Mariana Rossi

Journal of the American Chemical Society 2019 141 (6), 2526-2534

DOI: 10.1021/jacs.8b12471

I was not able to locate the any information how i-PI can use an ORCA client as the authors of the publication were.

Was I not looking in the right place, or is that client not public? If ORCA needs patching, that would explain things.

Thanks,

Gabor

Michele Ceriotti

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Mar 27, 2020, 9:51:21 AM3/27/20

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I don't think we have ever released an ORCA official client, so you probably need to get in touch with Jeremy and Mariana, I'm sure they'll be glad to share.

Perhaps you could help making sure that the patch makes it back to the official ORCA package.

Cheers

Michele

venkat kapil

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Mar 27, 2020, 10:01:30 AM3/27/20

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If an ASE Calculator exists for ORCA, you could perhaps get it to work with i-PI using ASEClient() (see examples/ASEClient/ in the i-PI repo).

Mariana Rossi

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Mar 27, 2020, 11:04:16 AM3/27/20

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Ops! I am always late here, sorry. I'll copy/paste the answer I gave to Gabor in a private e-mail to make the info available:

Hi Gabor,

ORCA cannot be immediately used as a client to i-PI and we did not do that in our paper. We have only used ORCA as a benchmark tool, and there fore only optimized geometries and evaluated energies with it. We do not write anywhere that ORCA was used as an i-PI client in that paper, only FHI-aims was.

However, you can use ORCA as an indirect i-PI client through ASE. The way it works is that you set ASE as a client from i-PI and ORCA as the calculator of ASE. The drawback is that the way ASE works, it does not keep its calculator “alive” between two steps, so each MD step means a full reinitialisation from scratch of the electronic structure code.

As far as I am aware, the developers from ORCA have not expressed interest in coding an interface, but if you are in contact with any of them, we (the i-PI developers) are happy to provide guidelines.