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<pre wrap="">Hello Dr. Tran,
I believe I have located the problem. The SCF cycle did not fully converge before the density gradient was calculated. Running SCF to full convergence should ameliorate this issue.
Thank you,
-Neil Johnson, B.Sc. </pre>
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On 12-07-11 1:22 AM, <a class="moz-txt-link-abbreviated" href="mailto:tran@theochem.tuwien.ac.at">tran@theochem.tuwien.ac.at</a> wrote:<br>
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cite="mid:Pine.LNX.4.64.1207110909400.4217@ar.theochem.tuwien.ac.at"
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<pre wrap="">In principle, GRR should not be negative because it is the average of
|∇ρ|/ρ (note that it's the norm) in the unit cell volume.
In output0_grr, there is
TOTAL= *************
for the PLANE WAVE CONTRIBUTION, which means that the problem comes from
the interstitial region. I would guess that this comes from some numerical
instabilities.
Such problems car arise close to the nucleus of very atoms or in regions
of space with low electron density. Is it the case in your system?
For the moment, I can not say much more.
F. Tran
On Tue, 10 Jul 2012, Neil Johnson wrote:
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<pre wrap="">Hello all,
I am attempting to perform an mBJ calculation using the steps listed in sec
4.5.8 of the user's manual. However, lapw0 keeps failing in the final scf
cycles after switching to IXC=28. We tracked the problem down to a negative
GRR (∇ρ/ρ = -36.0544), the square root of which is taken to calculate "c for
IXC=28" in lapw0. Taking the square root of a negative number is generally
frowned upon, and the program spits out a lot of "NaN"s before failing.
Has anyone experienced this problem before, or know what would cause lapw0
-grr to produce a negative GRR value?
I've posted the output0 and output0_grr files to
<a class="moz-txt-link-freetext" href="http://homepage.usask.ca/~nwj781/lapw0/">http://homepage.usask.ca/~nwj781/lapw0/</a>
<a class="moz-txt-link-rfc2396E" href="http://homepage.usask.ca/%7Enwj781/lapw0/"><http://homepage.usask.ca/%7Enwj781/lapw0/></a> for reference. Thanks!
Cheers,
Neil Johnson
University of Saskatchewan
Saskatoon, Canada
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