At best of my understanding, the DOS "as is" in units of cell volume,
that is the unit cell volume is taken as unity, i.e. [ 1 / ( energy *
UnitCellVolume ) ] where UnitCellVoume=1.
To get it in units of cube meters, you should divide the DOS "as is"
by the unit cell volume. For example, if the unit cell volume were
50A^3, then a DOS of 1 in 1/eV becomes 2x10^28 in 1/(eVm^3), makes
sense?
Patrizio
Salman Zarrini <[email protected]> ha scritto:
So, that means Quantum-Espresso gives an extensive density of states,
right? if so, then it should have a Volume^-1 in its unit.
Regards,
Salman
On Sat, Nov 13, 2021 at 2:46 PM Stefano Baroni <[email protected]> wrote:
it depends on the volume of the unit cell. once you divide by it, you get
an intensive (volume-independent) quantity. sb
___
Stefano Baroni, Trieste -- http://stefano.baroni.me
On 13 Nov 2021, at 20:29, Salman Zarrini <[email protected]> wrote:
Dear Giovanni,
Thanks for your response.
Then, considering the density of states in an electronic system and what
Quantum-Espresso calculates as the density of states, should we expect to
have a volume-independent quantity? if I understood you correctly!
Regards,
Salman
On Sat, Nov 13, 2021 at 1:30 PM Giovanni Cantele <
[email protected]> wrote:
Dear Salman,
Actually, the two definitions are not mutually exclusive. The first you
speak about, is the density of states per unit volume and, as you correctly
mention, has units Energy^-1 Volume^-1. However, the definition of density
of states a system of electrons and has units Energy^-1:
DOS(E) = sum_i Dirac_delta(E-E_i)
Integral( dE DOS(E) ) = number of electrons
What Quantum-Espresso calculates, is the density of states of the
electron system in the unit cell of a given Bravais lattice (due to
periodicity, you refer to the primitive cell). If you plot it as is, you
should give it units eV^-1. However, you could need the density of states
per unit volume. In that case, you can easily obtain the unit cell volume
of your system, divide the computed density of states by it, and then the
resulting density-of-states-per-unit-volume has units eV^-1 au^-3 (if you
express the volume in au^3).
In this case, if you integrate over the energy, you obtain number of
electrons per unit volume, that is, electron density.
Giovanni
> On 13 Nov 2021, at 19:14, Salman Zarrini <[email protected]>
wrote:
>
> Dearl all,
>
> As the density of states's definition implies, the electronic density
of states has a unit of "Number of electronic states per Energy per Volume"
or simply Volume^-1 Energy^-1. However, the "Volume^-1" is apparently
missing in the unit of density of states in literatures as well as here in
manual/tutorials of Quantum-Espresso. So that the Energy^-1 is used as the
unit for total density of states, atomic site projected density of states
and orbital projected density of states.
>
> I guess it is just a misunderstanding from my side, so, I would be
thankful if one could elaborate further on that.
>
> Regards,
> Salman
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_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
--
Patrizio Graziosi, PhD
Research Scientist
CNR - ISMN
Institute for the Study of Nanostructured Materials
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