[Pw_forum] misunderstanding on code to determine Fermi energy

[W. YU]

Dear PW users,

I read some of the codes from PW to determine the
Fermi energy - namely sumkg,efermig and other related
ones. I can't understand something here.

In function
sumkg(et,nbnd,nks,wk,degauss,ngauss,e,is,isk), the
parameter 'isk' could be 1 or 2 to determine the spin
components: 1 for up and 2 for down. Then the function
calculate the number of states at a given energy e. 

If I am right, 'is' could also be 1 or 2 to choose
spin component for calculating states. This way, the
total number of states seems for one spin only (i.e.
roughly half of nelec). But in function efermig, the
so calculated number of states is compared with nelec.
So I know I must have some misunderstanding in this.
Could anybody clear my mind?

Thanks!

W. YU 


 
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