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<div class="moz-text-flowed" style="font-family: -moz-fixed;
font-size: 12px;" lang="x-western">In this specific case, as
dispersion correction is a relatively new addition to the code, it
<i class="moz-txt-slash"><span class="moz-txt-tag">/</span>may<span
class="moz-txt-tag">/</span></i> also be caused by some minor
bug causing energy and forces to not be perfectly consistent. I
can tell from experience that even a difference as small as 10<sup
class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>-5</sup>
Ry can cause BFGS to fail when close to the minimum.
<br>
<br>
It would take some very careful finite difference calculation to,
possibly performed by someone who knows the dispersion correction
code, to be 100% sure. However I would say that for most purposes
you can proceed with no worries, and eventually use damped
dynamics for the last part of the geometry optimization.
<br>
<br>
regards
<br>
<br>
<br>
On 09/22/2014 09:52 PM, Paolo Giannozzi wrote:
<br>
<blockquote type="cite" style="color: #000000;">This kind of
errors invariably happens when you are very close
<br>
to the minimum and you have some numerical noise on forces. It
<br>
is useless in my opinion to insist: your system is sufficiently
<br>
relaxed
<br>
<br>
Paolo
<br>
<br>
On Mon, 2014-09-22 at 13:29 +0530, amitharani wrote:
<br>
<blockquote type="cite" style="color: #000000;">Hi
<br>
I am getting an error { Error in routine bfgs (1): dE0s is
positive
<br>
which should never happen }. The output file is attached for
your kind
<br>
perusal.This is the 2nd time I am getting the same error
consecutively.
<br>
I followed what Nick had suggested on the pwforum to take the
relaxed
<br>
co-ordinates, make a new input file and resubmit, but it
didn't
<br>
work.Thanks.
<br>
<br>
<br>
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</blockquote>
</blockquote>
<br>
<div class="moz-txt-sig"><span class="moz-txt-tag">-- <br>
</span>Lorenzo Paulatto - Paris 18
<br>
<br>
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