[Pw_forum] Fermi Energy of Cu

[Lorenzo Paulatto]

On 05/14/2013 10:49 PM, Jennifer Wohlwend wrote:
> Thank you for your reply, I guess I thought that, for metals, the 
> printed Ef was accurate and was not simply an absolute energy.

It is totally accurate, but it is only meaningful with respect to the 
occupied bands structure.

If you want to estimate the position of Ef with respect to the vacuum, 
i.e. the energy required to pull out an electron from the metal a.k.a. 
work-function, you first need to define what "out" is, which is 
non-trivial in periodic boundary conditions.

This problem is tackled in the WorkFct example, in PP/examples:
WorkFct_example:
     This example shows how to use pw.x, pp.x, and average.x to
     compute the work function of a metal using the slab-supercell
     approximation.  This example is of a 4 layer unrelaxed Al(100) slab
     with 5 equivalent layers of vacuum between the surfaces.

good work

-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone:+33 (0)1 44275 084 / skype: paulatz
www:  http://www-int.impmc.upmc.fr/~paulatto/
mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 5

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