From NWChem
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8:04:46 AM PST  Sat, Nov 19th 2011 

I have been running calculations on fluorinated vanadylnapthalocyanate, and was having some issues with convergence and bad molecular orbitals. I talked to a theoretical chemistry professor who suggested I add "task scf optimize" before dft in my input file. By running a hartreefock first, it should make the transition to dft easier and have fewer problems. However, my job came back with the following error pertaining to scf:
scf: no. of closedshell electrons is not even!
I googled this error message, and found that the only solution is to "define multiplicity." What does this mean, and how do I do it?
Thank you!




Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop


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8:50:58 AM PST  Mon, Nov 21st 2011 

Hi,
Can you post or send us your input file ?
Thanks.
Best,
Niri
Niri Govind
niri.govind@pnnl.gov





3:17:22 PM PST  Tue, Nov 22nd 2011 

start voncfjob11
ECHO
ECCE_PRINT /dtemp/bock788/VONcF/VONcFjob11/eccejob11.out
charge 0
geometry units angstroms
[coordinates would be here]
symmetry c4v print
end
basis spherical
V library 631g*
end
driver
maxiter 300
end
task scf optimize
dft
vectors input hcore
mult 2
iterations 300
xc pbe0
end
task dft optimize
task dft property
property
dipole
end
Also, if you have any information about "restarting" a job, that would be helpful. I was told to use this format for a restart, but the job was unable to run:
restart voncfjob11
permanent_dir /dtemp/bock788/VONcF/VONcFjob11
ECHO
ECCE_PRINT /dtemp/bock788/VONcF/VONcFjob12/eccejob12.out
When I tried to do this, I got an error with line:0
Thank you!




Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop


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Posts 79


12:20:39 AM PST  Wed, Nov 23rd 2011 

Hi,
With regard to your first question:
charge 0
geometry units angstroms
[coordinates would be here]
symmetry c4v print
end
Have you checked to see if more atoms are being created as a result of the symmetry specified ?
Perhaps you want to do the following:
geometry units angstroms
[specify the coordinates of all the atoms]
end
Let the code determine the symmetry.
Best,
Niri
niri.govind@pnnl.gov




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Posts 37


7:57:38 AM PST  Thu, Nov 24th 2011 

The reason seems to be that you calculate singlet with HartreeFock for (assumed in dft part) doublet.
Count the electrons in the system and set the correct multiplicity.
For HartreeFock:
http://www.nwchemsw.org/index.php/HartreeFock_Theory_for_Molecules#Wavefunction_type
for dft with:
http://www.nwchemsw.org/index.php/Density_Functional_Theory_for_Molecules#ODFT_and_MULT_...
In my impression (i may be wrong  don't know your system)
doing initially Hartree Fock geometry optimization and/or hybrid DFT is an overkill.
Maybe try just with PBE, and refine your results with PBE0 later.
This will offer you also a possibility to check dependence of your results on functional.
Note also that sometimes nonphysical systems show convergence problems.
Or problems could be related to the basis set you use, maybe try ECP's (http://www.nwchemsw.org/index.php/ECP)?
Check the example in the Nwchem source:
QA/tests/cu2_m06l/cu2_m06l.nw
I don't know what properties you are interested in, but the tiny 6311G/631Gs basis will give you error of tenths of kcal/mol
in atomization energy of a medium/large (~50 atoms) Vanadium complex.



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