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Re^3: Starting virtual orbitals for MCSCF

Alex Granovsky
gran@classic.chem.msu.su


Pavel,

>I got a NBO license. May i ask you some questions about this module.
>I did SP calculation using $nbo file=.... plot $end line. I got NBO's files. NBO orbitals in the PUNCH file corresponds to the NBO orbital from *.37 file, do they? Is it enough to use NBO orbitals as initial orbitals for MCSCF or should I also look into different NBO files?

I'd suggest to visualize NBOs using ChemCraft and select active space.

Then add

 $nbo aonbo $end 

to the input and you'll get NBOs in the punch file as well:

NBOs in the AO basis:                                                           
 $VEC....




>Is there any trick i should know for non-singlet systems? I saw, beta and alpha orbitals are different.

I can only recommend to inspect both sets.

Also, check papers containing "CAS/NBO" keyword. The base paper is:

http://scitation.aip.org/content/aip/journal/jcp/97/2/10.1063/1.463289

Kind regards,
Alex





>Any comments maybe not form you, but from any user of NBO code in FF will be useful.

>Pavel.
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>On Thu Mar 6 '14 6:51pm, Alex Granovsky wrote
>---------------------------------------------
>>Hi,

>>if you have NBO license you can try to visualize and use NBOs.

>>Kind regards,
>>Alex Granovsky
>>
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>>
>>On Thu Mar 6 '14 6:38pm, Pavlo Solntsev wrote
>>---------------------------------------------
>>>Hi,

>>>Maybe somebody had this problem before. I am working on a system with two copper centers. THis system was found to be multireference in nature. I have already done some calculations and solution looks good that makes me happy. However, i need to expand my active space. I need to include some 3d-orbitals from coppers (they were not included before) and corresponding 3d' virtual orbitals to keep active space balanced. I started from CIS-NO. All 3d orbitals may be found easily. However, situation with virtual orbitals is not so simple. I may see some virtual orbitals of d-character but very delocalized over coppers and ligands. I also checked VVOs orbitals from GAMESS-US but it doesn't solve the problem. The worst thing is i need to include not all 3d orbitals but only xz,yz and z2 (square-planar copper(II)). How can i purify my virtual orbitals to make them more localized?

>>>Thank you for any help.
>>>Pavel.
>>>


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