[Pw_forum] electron configuration of Ni

[Heather Kulik]

Dear Masoud,

You are correct in that the pseudopotential was generated in the state 3d9
4s1.

One minor point is that according to NIST (
http://physics.nist.gov/PhysRefData/ASD/levels_form.html), the low-lying
experimental atomic energy levels of Ni are:

^3F(3d84s2) ~0 and ^3D(3d94s1) ~ <0.1 eV, ^1D(3d94s1) ~ <0.5 eV.

However, the good news is that, the state in which the pseudopotential was
generated should not prevent you from accurately describing states that have
3d84s2 character since the core electrons from a 3d94s1 and 3d84s2 Ni should
be described fairly similarly.

You can also verify the character of your electronic states using any of the
postprocessing codes (e.g. projected density of states from projwfc.x)

Note: A more serious problem is that if your extended system (i.e. more than
one atom) has numerous solutions close in energy comparable to the character
of the atomic system, most x-c functionals will likely fail to predict the
correct ordering.

You should try comparing the relative energies you get for a few
representative systems to experimental data where possible to identify if
 the GGA (or LDA) suffers from any particular bias in the relative ordering
of these states.

Hope that helps!
--
Heather K
Postdoc at Stanford University


On Wed, Dec 15, 2010 at 12:31 AM, Masoud Nahali <masoudnahali at live.com>wrote:

> Dear Quantum Espresso Users
>
> I have used Ni.pbe-nd-rrkjus.UPF pseudo-potential for nickel in my project.
> In the info part of this pseudopotential has been written :
>
> Info:   Ni PBE 3d9 4s1 RRKJ3 US
>
> But I know that the well established electron configuration for nickel is
> "3d8 4s2" and now I am too worry that it may cause an error in my work. May
> it ?
>  I appreciate your help to understand the point in advance. Many Thanks
>
>
>
> Best Wishes
>  *
>
> -----------------
>
> Masoud Nahali
>
> PhD Student of Physical Chemistry
> Sharif University of Technology
> *
>
>
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