[Q-e-developers] Problems converging anions in vacuum

[Stefano de Gironcoli]

my little contribution..
one thing that one can try is to use martyna-tukerman (that should set  
the potential reference such that it vanishes  for r=\infty ) and add 
iprint=1 that prints eigenvalues at each iteration.
in this way one can see whether there is some sudden jump in the 
eigenvalues and if some of them approach or exceed zero.

stefano

On 05/11/2012 12:04 PM, Oliviero Andreussi wrote:
> Just to make things more reproducible, I rerun some tests with clean 
> versions of QE, both the svn and the 4.3.2, the latter also using the 
> gamma only algorithm, you can find the input and outputs attached. 
> There are some small differences in the numbers, but the overall 
> effect is the same, the SCF goes nuts. I would like to stress that the 
> problem is not system specific, the same happens for the input atomic 
> positions translated or in larger cells, with or without 
> martyna-tuckerman correction, and the same happens for many anions (10 
> out of 60, including OH-), even though all these tests were performed 
> with a local version of QE. As I said briefly in the previous email, 
> the local modifications do nothing for this specific calculations, 
> i.e. anions in vacuum, and actually when you include a dielectric 
> medium the calculations do converge. I understand that it is always 
> better to be extremely careful with local modifications, but after the 
> tests of today I would be even more confident that the problem is in 
> QE, not in our version.
>
> Oliviero
>
> On 05/10/2012 10:46 PM, Paolo Giannozzi wrote:
>> It should be helpful to know if the same phenomenon
>> (which seems to me clearly pathological) exists in an
>> unmodified version of QE and with K_POINT gamma
>> as well.
>>
>> P.
>> ---
>> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>> Phone +39-0432-558216, fax +39-0432-558222
>>
>>
>>
>>
>
>
> _______________________________________________
> Q-e-developers mailing list
> Q-e-developers at qe-forge.org
> http://qe-forge.org/mailman/listinfo/q-e-developers

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/developers/attachments/20120511/91be7f6b/attachment.html>