[Wien] Checking the effect of pressure on the bandstructure

[Víctor Luaña Cabal]

On Thu, May 07, 2015 at 10:01:15AM +0300, amit ribak wrote:
> ​Hello,
> 
> I'm interested in checking the effect of pressure (uni-axial) on the band
> structure. I first calculated the band structure with and without
> spin-orbit interaction and was able to restore previous results.
> Now, I want to see how the pressure affects the band structure. How can I
> incorporate this into Wien2k?
> 
> The c over a optimization is the way to do it or I simply need to change
> the lattice parameters of the initial structure?

Amit,

1) Use thermodynamics

2) Your wien2k calculation is giving you the internal energy:
   E = U(S,V), nominally at 0K, no zero temperature effect, and 0Pa.

3) To analyze pressure effects you can analyze the enthalpy or the
   Gibbs funcion:

   H(S,V) = U + pV
   G(T,p) = U + pV -TS

   If you have enough information on the vibrations of your system try
   to study G, clearly. The zero temperature effect (ZPE, zero point
   energy) has not been deeply studied in this field of solid state.
   It is an interesting subject to explore better.

4) Look for papers in Phys Rev B on this subject. I have mine
   available, so forgive me for citing mainly my publications on this
   subject. The most recent are articles by Alberto Otero-de-la-Roza
   and myself. For example:
   Phys. Rev. B 84 (2011) 184103

5) On Computer Phys Commun you have freeware codes to do this task.
   Look for the gibbs, asturfit and gibbs2 programs.

6) Notice that the codes in (5) are truly devoted to hydrostatic
   conditions, no uni-axial situations. For that I would recommend
   analyzing the grand potential

   \Omegai(T,p,\vec{\mu}) = U +pV -TS - \vec{n} \vec{\mu}

   (Sorry for the tex jargon)
   If you want to analyze a pure substance, remember that
   $\mu = g = G/n$, and \vec{n} = n.

Best regards,
             Dr. Víctor Luaña
--
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! Dr.Víctor Luaña, in silico chemist & prof. ! 
! Departamento de Química Física y Analítica ! 
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