Miro,
but isn't the KRMCSF code limited to a single state?
-Kirk
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Maybe, but I would be worried that as I neared dissociation my underlying spinors are going to be strongly biased towards a particular dissociation channel (one of three in the current case) of the state I chose for the KRMCSCF. That's then asking a lot for the KRCI to make up for (particularly when you typically have to truncate the virtual space as well to make it manageable). You will certainly never recover the correct degeneracies at long range with this approach.
A state-averaged KRMCSCF would be really nice. :)
best regards,
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On 4 Aug 2021, at 19:16, 'Peterson, Kirk' via dirac-users <dirac...@googlegroups.com> wrote:
Maybe, but I would be worried that as I neared dissociation my underlying spinors are going to be strongly biased towards a particular dissociation channel (one of three in the current case) of the state I chose for the KRMCSCF. That's then asking a lot for the KRCI to make up for (particularly when you typically have to truncate the virtual space as well to make it manageable). You will certainly never recover the correct degeneracies at long range with this approach.A state-averaged KRMCSCF would be really nice. :)best regards,-KirkFrom: <dirac...@googlegroups.com> on behalf of "Ilias Miroslav, doc. RNDr., PhD." <mirosla...@umb.sk>
Reply-To: "dirac...@googlegroups.com" <dirac...@googlegroups.com>
Date: Wednesday, August 4, 2021 at 10:09 AM
To: "dirac...@googlegroups.com" <dirac...@googlegroups.com>
Subject: Re: [dirac-users] Fock space does not converge
Indeed, it is, but the following KRCI - upon good molecular spinors - can describe multiple states,http://diracprogram.org/doc/master/manual/wave_function/krci.html#ciroots .
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Dear Dirac experts,
I’m still trying to calculate PECs of the low-lying doublet states of the LiSr molecule, which belong to the first three dissociation limits (see above).
Now I use KRCI/cc-pCVTZ level of theory (spin-free), but I have the same problem: the energies of three states, which should belong to the third dissociation limit (Li(^2P)+Sr(^1S), 14903-14904 cm-1), are too overestimated (20037-20684 cm-1).
Could this be related to incorrect choice of the GAS shells? Or is it something else?
Thanks in advance,
Maksim.
Dear Johann,
Thanks for your answer.
The above calculation was performed with spin-free ECP for the Sr atom especially in order to see main regularities. I think that origin of the 20037-20684 cm-1 splitting is rather splitting between Pi (first two values) and Sigma (last value) molecular terms, than atomic (Li) SOC splitting. At least, for a distance of 20 A, this splitting is absent.
I am attaching two more files. The first of them is a calculation with spin-orbit ECP for the Sr atom, and the second one is calculation within an all-electron basis set.
Thanks in advance,
Maksim.