Calculation of Wannier centers and spreads

Marcella Iannuzzi marci... at gmail.com
Fri Jul 17 20:10:05 CEST 2015


Dear Yannis,

The molecular dipoles are a good quantity to check.

ciao
Marcella

On Friday, July 17, 2015 at 1:37:19 PM UTC+2, iskarmou wrote:
>
> Dear Marcella,
>
> thanks for your reply.
> I tried the Jacobi algorithm as well and I have
> seen that in general less iterations were required (with the
> same tight convergence).
> However the convergence parameter, as you say, is too tight.
> The reason I used this value is not really based upon strong scientific
> arguments, it's because I have seen several people using tight criteria.
> Regarding the effect of convergence parameters on the results, which thing 
> do you think that it would
> be the most appropriate to check? 
> Should I calculate eg the dipoles from the Wannier ions_center trajectory 
> file using different convergence criteria?
> Or the spreads as well?
> Is there another way to check this effect?
> And do you know if there is any "optimum" value for the convergence 
> parameter for these kind of systems?
>
> Best regards
>
> Yannis 
>
> On Wednesday, July 15, 2015 at 9:53:48 AM UTC+1, Marcella Iannuzzi wrote:
>>
>>
>> Dear Yannis, 
>>
>> Probably the localisation algorithm requires many iterations to converge.
>> Are you sure that you need such a tight convergence for EPS_LOCALIZATION?
>> Did you check whether a less tight value really affects the results?
>> You can try to replace CRAZY with JACOBI, maybe it converges faster. 
>>
>> regards
>> Marcella
>>
>> On Saturday, July 11, 2015 at 1:06:49 PM UTC+2, iskarmou wrote:
>>>
>>> Dear all,
>>>
>>> I am simulating a mixture of H2O-CO2 and after 
>>> an equilibration period of 4 ps I am performing
>>> a productive run to calculate the system properties.
>>> Among these properties, I want to calculate
>>> Wannier centers and spreads.
>>> I am using the following method (I attach the corresponding part of the 
>>> input file):
>>>
>>>      &LOCALIZE
>>>
>>>      METHOD CRAZY
>>>      EPS_LOCALIZATION 1.0E-8
>>>
>>>      &PRINT
>>>         &WANNIER_CENTERS
>>>           &EACH
>>>             MD 1
>>>           &END EACH
>>>           IONS+CENTERS T
>>>           FORMAT XMOL
>>>           FILENAME ./ions+centers.xyz
>>>           COMMON_ITERATION_LEVELS               3
>>>         &END WANNIER_CENTERS
>>>
>>>         &WANNIER_SPREADS
>>>           &EACH
>>>             MD 1
>>>           &END EACH
>>>           FILENAME ./wannier-spreads
>>>           COMMON_ITERATION_LEVELS               3
>>>         &END WANNIER_SPREADS
>>>
>>>       &END PRINT
>>>     &END LOCALIZE
>>>
>>> However, the run is significantly slower in comparison with the
>>> previous runs, when I was not calculating Wannier centers and spreads.
>>> Is there any way, from a methodology and technical point (eg parameter 
>>> choice) of view, to speed up my calculation
>>> without losing the accuracy in the estimation of the Wannier centers?
>>>
>>> Thanks in advance
>>>
>>> Yannis Skarmoutsos
>>>
>>
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