[Pw_forum] Simulated annealing

[Stefano Baroni]

Yet another bit of clarification:

On Jul 26, 2005, at 8:57 AM, Paolo Giannozzi wrote:

> On Tuesday 26 July 2005 17:26, Yonas Abraham wrote:
>
>
>> One way is to use cp.x (Car-Parrinello MD) that comes
>> with the espresso package. The simple step would be
>>
>> -minimize the wavefunction
>> -minimize the geometry
>> -heat the system
>> -turn the temperature off and let the geometry relax

This is not quite "simulated annealing", but rather "simulated  
quenching". Simulated annealing requires a real-time control of  
temperature (not just "on/off") which I do not know if it is  
available in either code, but which should be not so difficult to  
implement, should anyone be interested.

SB

>>
>> But I don't know if there is such thing on the pw.x.
>>
>
> just a clarification: simulated annealing is something distinct
> from Car-Parrinello dynamics. The above steps can be performed
> either with "Born-Oppenheimer" dynamics (i.e. with electrons
> always on the ground state) or with Car-Parrinello dynamics
> (i.e. with an additional dynamics on electrons that keeps them
> close to the groung state). The latter case is not implemented
> in PWscf: one has to use either CP or FPMD, both part of the
> quantum-espresso distribution.
>
> Also note that temperature control in the current release of
> PWscf is not very sophisticated.
>
> Paolo
> -- 
> Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
> Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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