From NWChem
Viewed 3933 times, With a total of 5 Posts


1:36:15 PM PST  Wed, Jan 11th 2012 

Hi,
I am doing a DFT property calculation to evaluate the Mulliken population (Property ; Mulliken ; end [...] Task DFT property). I noticed that the property module changes the convergence criteria from the defaults to make them more stringent as you can see from the following output lines :
NWChem Property Module

itol2e modified to match energy
convergence criterion.
NWChem DFT Module

Convergence on energy requested: 1.00D07
Convergence on density requested: 1.00D05
Convergence on gradient requested: 1.00D06
Screening Tolerance Information

Density screening/tol_rho: 1.00D11
Is there a way to override this in order to keep the default thresholds and speed up the calculation?
Thanks,
Chloe




Edoapra Forum:Admin, Forum:Mod, bureaucrat, sysop


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5:55:23 PM PST  Fri, Jan 13th 2012 

Insert "task dft energy"

Chloe,
If you inser the line "task dft energy", the energy calculation will be run with the default convergence threshold for energy (or even looser, if you redefine them in the dft input field), e.g.
start hh
geometry
h 0. 0. 0.
h 0. 0. 1.
end
basis
* library sto3g
end
Property ; Mulliken ; end
dft
convergence energy 1d6
end
task dft energy
task dft property





8:13:17 AM PST  Mon, Jan 16th 2012 

Thanks, but this still reconverges the DFT with an energy threshold of 1e7 when the property is evaluated. That is what I am trying to avoid. Is there a way of only evaluating the property using the vectors converged during the energy calculation?
Chloé




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


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Posts 597


3:43:28 PM PST  Tue, Jan 24th 2012 

You may want to try setting "mulliken" in the DFT block itself. It should perform a basic Mulliken analysis there too.
Alternatively, there is a little known feature in the code that would prevent the recalculation of the vectors. When you specify a specific set of vectors in the property block it should just use those without recomputing.
start hh
geometry
h 0. 0. 0.
h 0. 0. 1.
end
basis
* library sto3g
end
property
Mulliken
vectors hh.movecs
end
dft
convergence energy 1d6
end
task dft energy
task dft property
A second option is to use the following input block, where the prop:nocheck parameter that's get set avoids DFT setting a tighter convergence for the property calculation.
start hh
geometry
h 0. 0. 0.
h 0. 0. 1.
end
basis
* library sto3g
end
property
Mulliken
end
dft
convergence energy 1d6
end
task dft energy
set prop:nocheck .true.
task dft property
Bert
Quote: Jan 16th 3:13 pmThanks, but this still reconverges the DFT with an energy threshold of 1e7 when the property is evaluated. That is what I am trying to avoid. Is there a way of only evaluating the property using the vectors converged during the energy calculation?
Chloé



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