[Wien] How to simulate the ionic state of a compound?

[pieper]

High, Abderrahmane,

> If I introduce the Ni atom and I change the Z number to 27 or 26 it
> still nickel because the atom is ont only Z and I change Z the number
> of neutrons and protons still inchanged.

NO! Z is the NUCLEAR charge. It sets the number of electrons 
automatically. If you change that you have another element! Try it by 
entering only the chemical symbol (e.g. Ni) in the corresponding field 
of the w2web struct editor. Leave the field Z empty. Press 'save and 
continue editing'. It will have filled in the correct Z automatically. 
One can circumvent this automatism, but it only makes sense if you know 
what you do. As I said before: find out yourself, start with a text book 
and the UG. You might learn enough in the process to know what you are 
doing.

> An other question: We suppose that the ionic state of NiO is a result
> from the electron density , can we force this ionic state to be
> Ni+3S-3 and it's yes how?

Once again: You want to create some charge distribution of your own 
design where atom A lost electrons from and atom B caught them in what 
you decide is their own shell.

This is NOT what DFT or Wien2k does!

DFT gives you a (usually very good) approximation of where the electrons 
actually are in space. This may (in ionic crystals) or may not (with 
covalent or metallic bonds) agree more or less with your ideas.

Note that the agreement depends not only on the charge distribution 
itself! It heavily depends on how you decide by your experimental and/or 
computational methods which electron belongs where. Thats where the 
different definitions of charges Prof. Marks pointed out come from.

And try to get your hands on a good text book on solid state physics. It 
will help you far more than anyone in this mailing list can in his/her 
free time.

Best regards

Martin Pieper

---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 24.08.2017 02:23, schrieb Abderrahmane Reggad:
> Thank you for all for the rich discussion
> 
> If I introduce the Ni atom and I change the Z number to 27 or 26 it
> still nickel because the atom is ont only Z and I change Z the number
> of neutrons and protons still inchanged.As I mentionned when I have
> changed Z I have observed that the total energy changes.
> 
> An other question: We suppose that the ionic state of NiO is a result
> from the electron density , can we force this ionic state to be
> Ni+3S-3 and it's yes how?
> 
> Best regards
> 
> 2017-08-24 0:43 GMT+01:00 Abderrahmane Reggad <jazairdz at gmail.com>:
> 
>> Hello
>> 
>> The reason for my question is that I don't how does a DFT code work
>> and I want to know if the ionic state is a result or an assumption.
>> 
>> Thank you for contribution to clarify the picture.
>> 
>> Best regards
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