[Pw_forum] (no subject)

[Gabriele Sclauzero]

On top of what I said (assuming that your PPs are good): maybe you should also try to 
increase cutoffs of wavefunctions or charge density. You can first do a convergence test 
on the forces computed after a simple scf run (remember that forces are harder to converge 
than total energy).

GS

Gabriele Sclauzero wrote:
> My "semi-empirical" suggestion is to restart with ion_dynamics='damp' and see if the 
> problem persist. Maybe you can do a few steps of damped dynamics and then restart again 
> with BFGS. Probably this will not solve your problem, but you can give a try ;-)
> 
> HTH
> 
> GS
> 
> 
> PS: you should chose better the subject of your posts next time...
> 
> 
> Julen Ibanez Azpiroz wrote:
>> Hello
>>
>> I am trying to relax a system with unit cell made of 24 silicon atoms 
>> and 2 talium atoms, one in each edge. I wish the system to be a surface, 
>> so the unit cell has vacuum between the talium atoms so that they do not 
>> "see" each other. I tried to relax it following the Example03 of Quantum 
>> Espresso which is a surface of  "al001". In the example there are two 
>> methods, I followed the first one, the one of the "bfgs" method. When I 
>> use Scalar_Relativistic pseudopotentials (for both atoms) it is Ok, 
>> after some trials the system relaxes. However, when I use Relativistic 
>> pseudopotentials (for both atoms) the system cannot relax, after many 
>> trials the system repeats the atomic configuration and stops. I have 
>> tried both, to let all the atoms move and to let move just a few of the 
>> surface, keeping the other fixed, but it does not work anyway. The most 
>> I can get is that the force in every atom is smaller than 0.01Ry/au. 
>> Both pseudopotentials work allright in simpler models. I would 
>> appreciate any suggestion. Thank you very much
>>
>> Julen
>>
>> UPV/EHU, Fisica de la Matertia Condensada
>>
>>
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>>
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> 

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