[Pw_forum] Total DOS and sum of PDOS don't overlap

[Stefano de Gironcoli]

the integral of the dos on the energy axis (from -infty to +infty) is 
the total number of states in your system ... (the number of plane waves 
in your basis) .... can you figure out why ?
the integral of the total pdos over the same interval is the total 
number of atomic wavefunctions over which one is projecting ...   again, 
can you figure out why ?
As NPW >> NATOMWFC no surprise they differ in some portion of the energy 
axis.
Since approximations like LCAO are usually reasonable the occupied 
portion of the energy axis is usually  well described but sooner or 
later the pdos must drop to zero while the dos likely goes on for a 
while (forever for infinite cutoff).

hope this helps
stefano

Luis Martínez wrote:
> Dear QE users,
>
> I have performed a DOS calculation of a metal oxide system with some
> adsorbates.
> Then I plot the total DOS using the file myfile.pdos_tot, and I also plot
> the sum of the PDOS generated by the program sumpdos.x included in the
> Quantum Espresso package.
> In principle both plots should give the same, but what I see is that the DOS
> plots for the zone of the unoccupied bands do not overlap. In particular,
> the DOS area generated with the sumpdos.x program is considerably smaller.
> I can't understand why do I encounter this difference. Is there a reason for
> that?
>
> Thank you
>
>   
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