[Q-e-developers] smearing style

[stefano de gironcoli]

Dear Jiqianq
  the answer to your question depends on which physical quantity you 
want to calculate.
  Is the state you want to study spatially localized ? is it an isolated 
(narrow band) in a band energy gap ? are you interested in the shallow 
donor states formed by the holes at the bottom of the conduction band of 
a doped semiconductor ? Or is your system a metal ?
  clarifying to yourself what is the question you want to answer will 
help you to figure out how to compute a physically meaningful number.

stefano

On 19/09/2015 12:37, Jiqiang Li wrote:
> Dear Lorenzo,
>         For example, for a supercell with 100 electrons, it will be of 
> 99 electrons when the system is +1 charged. I consider the 50th band 
> as the highest occupied band with half occupation.
>
> Jiqiang
>
> ------------------------------------------------------------------------
>
>     *From:* Lorenzo Paulatto <mailto:paulatz at gmail.com>
>     *Date:* 2015-09-19 18:14
>     *To:* General discussion list for Quantum ESPRESSO developers
>     <mailto:q-e-developers at qe-forge.org>
>     *Subject:* Re: [Q-e-developers] smearing style
>     Dear Jiqiang,
>     the "highest occupied banda" are obviously defined only for
>     insulators, i.e.
>     there is no such thing as a highest occupied bands when using a
>     smearing, what
>     threshold do you use for occupied/non occupied?
>     kind regards
>     On Saturday, September 19, 2015 05:48:09 PM Jiqiang Li wrote:
>     > Dear developers,
>     >         I want to use the wavefunctions of highest occupied
>     bands  in a
>     > charged system to evaluate some quantities, such as psi_i(r)
>     ＊psi_j(r) .
>     > However, I found that the wavefunction sensitively depends on
>     the degauss
>     > value.  So, how to choose a suitable value for degauss when I
>     want  to
>     > obatain a physically meaningful quantity.
>     >
>     > Best regards!
>     >  Jiqiang Li
>     >
>     >
>     >
>     -- 
>     Lorenzo Paulatto - Paris
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>
>
>
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