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Re^6: MRCI

Maksim Shundalau

Dear Alex,

I thank you for your help, but the problem is the following:

In Molpro for CASSCF level of theory I have the energies:
-51.847066 (4.00 A), -51.847646 (4.10 A) and -51.847989 (4.20 A) and energy differences:
-0.000580 [E(4.10)-E(4.00)] and -0.000343 [E(4.20)-E(4.10)].

Then, in Molpro for MRCI level of theory I have the energies:
-52.338309 (4.00 A), -52.338409 (4.10 A) and -52.338304 (4.20 A) and
energy differences:
-0.000100 [E(4.10)-E(4.00)] and +0.000105 [E(4.20)-E(4.10)].

Thus, on passing from CASSCF to MRCI the energy decreases approximately 0.5 a.u. at each point, and minimum shifts from approximately 4.30 A to 4.00 A.

In Firefly for CASSCF level of theory and stage-averaging for 14 states I have the energies for ground state:
-51.847068 (4.00 A), -51.847688 (4.10 A) and -51.848076 (4.20 A) and energy differences:
-0.000620 [E(4.10)-E(4.00)] and -0.000388 [E(4.20)-E(4.10)].

In Firefly for CASSCF without stage-averaging (only for ground state) I have the energies:
-51.850576 (4.00 A), -51.851160 (4.10 A) and -51.851504 (4.20 A) and energy differences:
-0.000584 [E(4.10)-E(4.00)] and -0.000344 [E(4.20)-E(4.10)].

Thus, in Firefly for CASSCF I have the almost same energies (with SA) or the almost same energy differences as in Molpro.

However, in Firefly for MRCI I have (for example in 4.00 A) only -51.847243, i.e. the energy decreases ONLY on 0.000175 a.u. In your calculation the situation is similar (in 4.10 A): -51.847711 for CASSCF and -51.847866 for SOCI (is this MRCI?).

Can I get in Firefly the same energy decrease as in Molpro for MRCI level of theory?

Best Regards,

On Tue Nov 11 '14 11:56am, Alex Granovsky wrote
>Dear Maksim,

>I first computed MP2 natural orbitals, then converged CASSCF,
>then computed SOCI energy. Attached please find the input and
>output files. Hope this helps.

>Kind regards,
>Alex Granovsky
>On Thu Nov 6 '14 11:34pm, Maksim Shundalau wrote
>>Dear Alex,

>>Here are my explanations:

>>1) OK
>>2) Yes, I plan to compute excited states (at any rate 5 singlet states including ground state and 2 doubly degenerate states, and 5 triplet states including 2 doubly degenerate states; total 14 states) with state averaging procedure.
>>3) Since in that time I had a computer with a small memory (approx. 100 MWords). With next=50 I get approximately the same results.
>>4) 8
>>5) Since I plan to compute some excited states of different symmetry with state average procedure.

>>Best Regards,
>>On Thu Nov 6 '14 1:25pm, Alex Granovsky wrote
>>>Dear Maksim,

>>>I have several questions related to your input file. I hope your answer help me to help you.

>>>1) I guess the basis set you are using is spherical, (i.e., not  Cartesian), is it? You should use d5 option if so.

>>>2) Why do you use CAS(2e,10o)? It seems CAS(2e,5o) is enough.
>>>Moreover, CAS(2e,10o) is extremely ill-defined as orbital
>>>populations for five orbitals are very close to 0.0 Do you plan to
>>>compute excited states as well? It would be a good idea to include
>>>them into state averaging procedure if so.

>>>3) Why do you restrict SOCI by only 20 external orbitals?

>>>4) What is the number of core orbitals when running with molpro?
>>>With Firefly, it is 8. Check if it the same with molpro.

>>>5) Why do not you use molecular symmetry in the job?

>>>Kind regards,
>>>Alex Granovsky
>>>On Mon Nov 3 '14 3:58pm, Maksim Shundalau wrote
>>>>Dear Alex,

>>>>Here is the complete input file. The CASSCF energies for this and other points are quite close to the Molpro ones. But the MRCI energies are very far from them.

>>>>Best Regards,
>>>>On Wed Oct 29 '14 5:07pm, Alex Granovsky wrote
>>>>>Dear Maksim,

>>>>>could you provide the complete input and a basis set file?

>>>>>Kind regards,
>>>>>Alex Granovsky
>>>>>On Mon Oct 27 '14 11:15pm, Maksim Shundalau wrote
>>>>>>Dear Firefly users,
>>>>>>I'm trying to reproduce with Firefly some Molpro's results. For example, for the ground state of KRb molecule in MRCI/CASSCF(2,8) approximation with Stuttgart-type small core ECP with Molpro I get R(min)=4.10 A (quite close to the experimental 4.07 A value) and good asymptotic behavior for R=20 and more A.
>>>>>>But with Firefly I can't get similar results. I think I do something wrong (an example is below).
>>>>>>Could you explain to me where I'm wrong?

>>>>>>Best Regards.

>>>>>> $CONTRL SCFTYP=mcscf RUNTYP=energy EXETYP=run MAXIT=200 MULT=1
>>>>>>    ecp=read COORD=zmt cityp=guga $END
>>>>>> $SYSTEM TIMLIM=3600 mwords=400 $END
>>>>>> $GUESS GUESS=moread norb=194 $END
>>>>>> $mcscf maxit=400 cistep=guga fors=.false. $end
>>>>>> $drt group=c2v nmcc=8 ndoc=1 nval=7 next=0 soci=.true.
>>>>>>          iSTSYM=1 mxnint=31000000 $end
>>>>>> $gugdia nstate=1 CVGTOL=1.0E-06 ITERMX=400 $end
>>>>>> $cidrt group=c2v nfzc=8 ndoc=1 nval=7 next=0 soci=.true.
>>>>>>          iSTSYM=1 mxnint=31000000 $end
>>>>>> $gugdia nstate=1 CVGTOL=1.0E-06 ITERMX=400 $end
>>>>>> $DATA
>>>>>>Cnv 2

>>>>>>Rb  1    4.100000
>>>>>> $END
>>>>>> $ZMAT IZMAT(1)=1,2,1 $end
>>>>>> $ECP
>>>>>> $END
>>>>>> $VEC
>>>>>> $end

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