Store information about EOM-CC3


I want to restart EOM-CC3 calculations from the previous calculations, to save some time, since the EOM-CC3 calculation calculate just one root per run. How can I do this?

Searching the documentation, the RESTART_EOM_CC3 option is possible, but I think I need to put another configuration on the first run to save the files.

Best regards,

Alan Guilherme Falkowski.

EOM questions are normally for @crawdad.

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The restart options were developed for a much earlier version of Psi, so it’s likely not reasonable to try to keep the necessary files in place for this in Psi4. However, I would also suggest that this option is really only valuable when one runs out of iterations for a single excited state/root. If you want multiple roots, the option probably wouldn’t save you all that much time because the ground-state calculation and the EOM-CCSD guesses are still pretty inexpensive relative to the CC3 excited state calc. @Rollin_King can correct me if I’m off base here.

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Yep, what @crawdad said. Since Psi went to auto-naming its temporary files, it always takes me awhile to work out how to name and reuse them. But in this case, it would be of nearly negligible benefit.

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Thank you @jmisiewicz, @crawdad and @Rollin_King.
Something seems strange to me, the EOM-CC3 calculation for a root is taking too long to run. Is this implementation parallelized? What are the input flags to parallel this type of execution?

Fundamentally, an excited-state CC3 sigma vector is 4 times the work of a ground-state iteration. I haven’t used the code in a bit but 2 keywords may be important. There is an explicit loop in the main EOM CC3 engine that may be threaded if you have sufficient memory.

T3_WS_INCORE = boolean [false]
Set this to True which keeps some 3-virtual index quantities in core memory. That’s a big ask but CC3 is so cpu intensive you may find it useful anyway.

CC_NUM_THREADS = integer [1]
Increase this to use the explicit threading. You may be limited by the amount of memory available on the machine so some experimentation will be required. Anything less than your # of cores is worth trying.

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I will test these flags. Thank you very much!