[Pw_forum] Re: [Pw_forum]a question about the relationship between Fermi energy and stability

Eyvaz Isaev eyvaz_isaev at yahoo.com
Tue Sep 6 13:12:02 CEST 2005


The Fermi energy you calculate is not directly 
related to the crystal stability until you study its
position on the density of states. According to the
Hume-Rothery rule  the Fermi level is located in the
(pseudo)minimum of the DOS, reducing the total energy.

I assume it is difficult to say which structure is
more stable based on only total energies, because
there is no details of structures you studied.
Besides, hopefully, you have not 119.5Ry, but


--- Chaohao Hu <chaohao2002 at 163.com> wrote:

> Sorry, the unit of Fermi energy is eV.
> Dear pwscf users,
> During my calculations, if considering different
> crystal structure for a certain material, I obtained
> different total energies and fermi energies. 
> For example, for structure 1, its equilibrium total
> energy is 119.5 Ry and fermi energy is 8.0 Ry; for
> structure 2, its total energy is 119.1 Ry, but its
> fermi energy is close to 0.0 Ry. 
> Which is the more stable structure? 
> Now I am confused to this. Who can explain more
> details about this problem?
> Thanks in advance.

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