From NWChem
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		                        | 5:37:16 PM PST - Tue, Nov 8th 2011  | 
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		                        I have been trying to run DFT calculations on partially fluorinated vanadyl napthalocyanine (527 electrons) and unfluorinated vanadyl phthalocyanine (295 electrons) (both C4v symmetry, enforced) using simple basis sets (3-21g or 6-31g) and B3LYP as an exchange functional. While my jobs are successful, all of the outputs have included "symmetry fudging" and warnings about the HOMO and LUMO being degenerate. Some of the jobs barely reach convergence after 120 iterations. What can I do to improve my calculations? I am already using simple basis sets, so should I switch to HF instead of DFT? Here is one of my VONc-F16 input file without the coordinates: 
 
start voncfjob9 
 
ECHO 
ECCE_PRINT /dtemp/bock788/VONcF/VONcFjob9/eccejob9.out 
 
charge 0 
geometry units angstroms 
[coordinates here] 
symmetry c4v print 
end 
 
 
basis spherical 
end 
 
dft 
mult 2 
iterations 120 
xc b3lyp 
end 
 
 
driver 
maxiter 60 
 
end 
 
task dft energy 
 
And here are some of the common warning messages in my output files: 
 
Warning: spatial symmetry breaking in UKS: alpha =  2.15E-02 
d= 0,ls=0.0,diis     2  -4860.6199036872  2.46E+01  5.32E-03  4.58E+01    21.7 
 
 
Symmetry fudging 
Warning: spatial symmetry breaking in UKS: alpha =  3.09E-02 
d= 0,ls=0.5,diis    47  -4887.6388975884 -1.53E-06  1.64E-06  5.28E-06   189.5 
                                                    4.72E-07  5.19E-06 
 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
Warning - the HOMO and LUMO are degenerate and you are using symmetry. 
This can lead to non-variational energies and poor convergence. 
Modify the initial guess, or use an open-shell wavefunction, or turn 
off symmetry. 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
 
 
Thanks in advance, any help is greatly appreciated.
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                                  - 
                                     Bert  Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
                                    
                                  
 
                                 
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		                        | 2:29:56 PM PST - Fri, Nov 11th 2011  | 
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		                        It seems that the initial guess does not give you the best choice of orbitals using the atomic guess. A couple of approaches could work: 
 
1. Easiest is to try "vectors input hcore" in the dft block, which might give you slightly different orbitals that help the minimizer find its path. 
 
2. Run SCF for like 20-30 iterations (Use "scf ignore" so that the calculation is sure to continue) and use those vectors as an input for the DFT. 
 
Bert 
 
 
Quote:  Nov 9th 12:37 amI have been trying to run DFT calculations on partially fluorinated vanadyl napthalocyanine (527 electrons) and unfluorinated vanadyl phthalocyanine (295 electrons) (both C4v symmetry, enforced) using simple basis sets (3-21g or 6-31g) and B3LYP as an exchange functional. While my jobs are successful, all of the outputs have included "symmetry fudging" and warnings about the HOMO and LUMO being degenerate. Some of the jobs barely reach convergence after 120 iterations. What can I do to improve my calculations? I am already using simple basis sets, so should I switch to HF instead of DFT? Here is one of my VONc-F16 input file without the coordinates: 
start voncfjob9
 
ECHO 
ECCE_PRINT /dtemp/bock788/VONcF/VONcFjob9/eccejob9.out
 
charge 0 
geometry units angstroms 
[coordinates here] 
symmetry c4v print 
end
 
basis spherical
 
end
 
dft 
mult 2 
iterations 120 
xc b3lyp 
end
 
driver
 maxiter 60 
 
end
 
task dft energy
 
And here are some of the common warning messages in my output files:
 Warning: spatial symmetry breaking in UKS: alpha =  2.15E-02 
d= 0,ls=0.0,diis     2  -4860.6199036872  2.46E+01  5.32E-03  4.58E+01    21.7 
 
Symmetry fudging 
Warning: spatial symmetry breaking in UKS: alpha =  3.09E-02 
d= 0,ls=0.5,diis    47  -4887.6388975884 -1.53E-06  1.64E-06  5.28E-06   189.5 
                                                    4.72E-07  5.19E-06 
 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 Warning - the HOMO and LUMO are degenerate and you are using symmetry. 
This can lead to non-variational energies and poor convergence. 
Modify the initial guess, or use an open-shell wavefunction, or turn 
off symmetry. 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
 
Thanks in advance, any help is greatly appreciated.  
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