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Alex Granovsky

gran@classic.chem.msu.su

Dear Pavel,

sorry for the delayed feedback.

Yes you need to run this all as a single job,

once for singlets and second time for triplets.

Sure you can reuse converged orbitals as the input

for the MCSCF procedure using guess=moread to speed

things up.

Your first input file should contain at least:

$contrl scftyp=mcscf mplevl=2 $end $det pures=.f. wstate(1)=... $end $mcscf cistep=aldet iforb=.t. $end $xmcqdpt iforb(1)=-1,1,1 mult=1 inorb=0 $end

and second should contain at least:

$contrl scftyp=mcscf mplevl=2 $end $det pures=.f. wstate(1)=... $end $mcscf cistep=aldet iforb=.t. $end $xmcqdpt iforb(1)=-1,1,1 mult=3 inorb=0 $end

Hope this helps. Please let me know if you need some additional comments.

All the best,

Alex

On Tue Oct 16 '12 1:17am, Solntsev Pasha wrote

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>Dear Alex.

>One more thing to clarify out talk.

>Should i run XMCQDPT with all function you mentioned or i need run XMCQDPT with $mcscf iforb=.t. $end $xmcqdpt iforb(1)=-1,1,1 $end and then use optimized orbitals (XMCQDPT) for XMCQDPT run for singlets and triplets?

>Thank you.

>Pavel.

>

>

>On Wed Oct 10 '12 10:12pm, Alex Granovsky wrote

>-----------------------------------------------

>>Dear Pavel,

>>sorry for large delay on my side.

>>>Q1. ok, it sounds very interesting. So, if an order of states from

>>CAS-CI part is 1,1,1,0,1 we can setup kstate(1)=1,1,1,0,1 and

>>basically remove "undesired" state from PT2 part.

>>Exactly.

>>> Does it make sense?

>>There are some situations when this for sure makes (some) sense.

>>For instance, assume one is dealing with diatomic molecule.

>>The full symmetry group is either C_{inf}v or D_{inf}h

>>which is a non-abelian symmetry group. The effective Hamiltonian

>>is thus block-diagonal and (provided one is interested in states of

>>some particular symmetry type) one can remove other states from PT treatment.

>>> Is this equivalent to setting of the AVECOE and WSTATE (XMCQDPT)

>>arrays to be AVECOE(1)=1,1,1,0,1 and WSTATE(1)=1,1,1,0,1. If not, what

>>is the best strategy, to use kstate or avecoe/wstate? Or, maybe, we

>>can just use nstate/wstate/avecoe combination and forget about kstate.

>>No you in general cannot. Both avecoe and wstate applies to renumbered

>>CI states i.e. to state numbers generated after renumbering procedure.

>>In general, kstate and avecoe/wstate are more or less independent.

>>As to NSTATE/kstate, kstate provides the finer control.

>>

>>

>>>Q2. What if those additional eigenvectors contribute to some low

>>lying states? Do we need repeat CASSCF part once again and include

>>those extra states?

>>The answer depends on the magnitude of contribution. If it is large

>>the answer can be "yes, it would be better to do that". As far

>>as I remember this self-consistent procedure of the selection of

>>the states in state-averaging was once discussed a year ago or so

>>on the forum, you may find my older comments on this.

>>

>>

>>>>>Q3: Is it good idea to do SA-CASSCF/XMCQDPT via singlets and triplets

>>>>simultaneously in case of high spin-orbit coupling. Actually, i am

>>>>going to check singlets only and singlets-triplets, but maybe it make

>>>>no sense.

>>>>I'd suggest you to use to use SA-CASSCF averaged over both singlet

>>>>and triplet states to generate the same set of MOs to be used in PT2

>>>>computations. Firefly v. 8.0.0 has some new features specifically

>>>>tailored for these types of jobs which I'll describe in my next post

>>>>to this thread.

>>>Yes, sure.

>>The couple of advises are:

>>1. Use aldet CASCI code with PURES=.f. to generate orbitals with SA-CASSCF.

>>2. Use

>>

$mcscf iforb=.t. $end $xmcqdpt iforb(1)=-1,1,1 $end

>>to generate and reuse the generated common set of canonical MOs and their energies

>>3. Perform two sets of QDPT calculations, one for singlets:

>>

$xmcqdpt mult=1 $end

>>and second for triplets:

>>

$xmcqdpt mult=3 $end

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>>Hope this helps.

>>All the best,

>>Alex

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Fri Oct 19 '12 0:57am

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