[Wien] DOS unit

[Peter Blaha]

The DOS is usually given in states/(eV unit-cell). Of course you can 
calculate the size of your cell and convert the DOS into your units. (As 
far as I know, all codes use the normalization per cell, never ever per 
volume.

The total DOS is often decomposed into some components, and this 
decomposition is slightly different in different codes/methods. Wien2k uses
a) a spatial decomposition (using the atomic spheres)
b) inside each sphere an lm-decomposition according to its basis set.
c) there is also some interstital DOS, which cannot be assigned to a 
particular atom.
We call this partial DOS.

In particular plane wave codes "project" the total wave functions onto 
some atomic orbitals. They use then projected DOS.

In any case, only the total DOS should in principle be identical between 
different codes. Every decomposition is method dependent.

The "local DOS" is something different. Actually it is NOT a DOS, but an 
electron density origination from states at a certain energy range 
(usually eg. one or two eV above/below EF). It is used for scanning 
tunneling microscopy simulations, where this "wrong" name was invented.


Am 04.02.2019 um 17:16 schrieb Salman Zarrini:
> Dear all,
> 
> As far as I know the density of states (DOS) is generally defined as the 
> number of electron states per unit volume per unit energy which simply 
> means that the unit of DOS should be states/(cm^3 eV) or states/(\AA^3 
> eV) in agreement with unit 1/(m^3 J) given for DOS in IUPAC Green Book - 
> Solid states section. Nevertheless, the unit assigned for DOS in most of 
> the literatures as well as here in Wien2k is just states/eV (or 
> state/energy) so that the 1/volume is somehow missing!
> So, I would be so thankful if one could elaborate where I am wrong and 
> what the proper unit for DOS is?
> One more issue (at least for me) is the concepts such as `` Projected 
> DOS'', `` Partial DOS'' and `` Local DOS'' which are heavily intermixed 
> in literatures, so, would you please let me know what the differences 
> among Projected, Partial and Local DOS are? And where each should be used?
> 
> Best regards,
> 
> Salman Zarrini
> Chemical Engineering Department
> Drexel University
> Philadelphia, PA, US.
> 
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