[Pw_forum] Phase Transition Pressures

Huolin Xin xinhuolin at gmail.com
Sun Apr 18 15:35:27 CEST 2010


Stefano, thanks a lot for pointing my mistake out. In the entropy term,
besides phonon and electronic entropy, how to calculate the structural
entropy?

On Sun, Apr 18, 2010 at 9:25 AM, Stefano Baroni <baroni at sissa.it> wrote:

> Dear Huolin: as explained in my previous post, I beg to differ. Phonons
> have nothing to do with the question asked by Cecil, as long as the
> temperature is low enough. Even less, the electronic entropy, as long as the
> the system insulating (even in metals, the electronic entropy play a very
> little role, below the Farmi temperature which is typically several
> thousands degrees ...). Even considering temperature effects, it is not the
> "free energy" that has to be made equal (usually, one indicates with this
> term the Helmholts free energy, E-TS), but the "Gibbs free energy"
> (E-TS+PV). Hope this clarifies a bit ... SB
>
> On Apr 18, 2010, at 3:04 PM, Huolin Xin wrote:
>
> You'll need phonon entropy and electronic entropy as well. Free energy is
> E-TS. The transition pressure is where the free energy of the two structures
> are the same.
>
> On Sun, Apr 18, 2010 at 5:39 AM, naphtaly moro <moronaphtaly84 at gmail.com>wrote:
>
>> Dear all,
>>
>> I am working on the pressure induced phase transitions of GaAs, I have
>> already obtained, the respective EV data for the structures and want
>> to get the transition pressures for the structures, Any advice on how
>> this can be done in Espresso?
>>
>> Thanks
>> Cecil Naphtaly Moro,
>> Mphil. Student,
>> Department of Physics,
>> Moi University, Chepkoilel Campus,
>> Kenya
>>
>> --
>> Cecil Naphtaly Moro
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
> ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
> http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
> stefanobaroni (skype)
>
> La morale est une logique de l'action comme la logique est une morale de la
> pensée - Jean Piaget
>
> Please, if possible, don't  send me MS Word or PowerPoint attachments
> Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html
>
>
>
>
>
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20100418/4fe1ff76/attachment.html>


More information about the users mailing list