Problems with negative frequencies


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Quote:Sergbuto Aug 16th 3:29 am
Following the advices in these threads
http://nwchemgit.github.io/Special_AWCforum/st/id2535/Trouble_with_negative_freque...
http://nwchemgit.github.io/Special_AWCforum/st/id2763/Frequency_Analysis_Grid_Dens...

I also used "grid huge" but it did not help either. Furthermore, the use of this option increased the calculation time to the extent that the numerical frequency calculation is faster with the "grid fine" option. The latter calculation gives only positive frequencies.

There seems to be a problem with analytical frequency calculations in NWChem.

Please try the following input. The major change is the line set dft:no_prune t. This is required for the correct integration of the contribution to XC potential from the Pu atom.
The associated output does not contain any negative frequency.
The input change increases the time to solution. We are working at a better fix that does not increase the time to solution.
start pco_new
echo

memory 6000 mb noverify
charge -5

geometry units angstroms
 O      4.72777782     0.00036022     0.00000000
 C      3.80305541    -0.95770261     0.00000000
 O      2.49547411    -0.62952538     0.00000000
 O      4.16561764    -2.23897376     0.00000000
 O      0.00000000     0.00000000     1.91098610
 Pu     0.00000000     0.00000000     0.00000000
 O      0.00000000     0.00000000    -1.91098610
 O     -0.14380067     4.72701758     0.00000000
 O     -1.79292203    -1.84638129     0.00000000
 C     -1.07213291     3.77239390     0.00000000
 C     -2.73092249    -2.81469129     0.00000000
 O     -2.36420087     4.09419559     0.00000000
 O     -0.70255209     2.47590666     0.00000000
 O     -4.02181697    -2.48804382     0.00000000
 O     -2.36357695    -4.09455580     0.00000000
end
BASIS spherical
Pu library "Stuttgart_RLC_ECP"
C library "Stuttgart_RLC_ECP"
O library "Stuttgart_RLC_ECP"
END

ECP
Pu library "Stuttgart_RLC_ECP"
C library "Stuttgart_RLC_ECP"
O library "Stuttgart_RLC_ECP"
END
dft
xc b3lyp
direct
vectors input atomic output PCO_new.movecs
iterations 5000
convergence energy 1d-10 damp 40 ncydp 0 dampon 1d99 dampoff 1d-4 
grid fine
smear
odft
mult 4
end

driver
xyz
tight
end

set int:txs:limxmem 25621940
set quickguess t
 
set dft:no_prune t
task dft optimize 

task dft freq