[Wien] How to decrease interstitial charges?

[Ahmad Ranjbar]

Dear Xavier,

Thank you very much for your information.


Best regards,


On Jul 26, 2010, at 3:26 AM, Rocquefelte wrote:

> Dear Ahmad,
> 
> Just to add one more comment. Such values are expected due to the high covalency of the chemical bond between carbon atoms in both graphene and diamond.
> 
> In fact, what you obtain is certainly values like (consider atom 1 as carbon):
> 
> CHA001 = 1.7  (which gives you the number of valence electron inside the MT sphere)
> 
> and
> 
> CTO001 = 3.7 (which gives you the number of total electron inside de MT sphere)
> 
> So as you mention 2 electrons are missing (in comparison to the atomic electronic structure 1s2 2s2 2p2), but the interaction is strong between carbon atoms (same electronegativity) and then an important part of the electronic density is in between the atoms (i.e. in the interstitial region). So a significant part of the charge should be in the interstitial region.
> 
> Lets take one of my examples to illustrate this feature. Sometimes ago I did calculation on vanadate compounds and the charge in the MT sphere of vanadium was as follow:
> 
> CHA = 1.818 for a vanadium 5+
> 
> CHA = 1.874 for a vanadium 4.5+
> 
> CHA = 1.899 for a vanadium 4+
> 
> As you see an increase of 1 electron in terms of formal charge lead to an increase of 0.081 electrons in the MT sphere !!!
> 
> So the variation is very small although in such a strong change from V5+ (with 3d0 electronic configuration) and V4+ (3d1).
> 
> So you can imagine that between graphene and diamond the change is smaller (same oxidation degree but different hybridation).
> 
> To conclude, when you are interested in the "real" charge of an atom you have to consider Bader charges or related tools (look at AIM program in WIEN2k).
> 
> Best regards
> 
> Xavier
> 
> 
> Ahmad Ranjbar a écrit :
>> Dear WIEN2K users,
>> 
>> I am doing some electronic structure calculations on graphene sheet using WIEN2K.
>> I am wondering if anybody can help me about my problem.
>> The problem is as follow:
>> 
>> My calculation shows that the total charge of carbon atom in muffin-tin sphere is about 4 electrons. It means that about 2 electron of Carbon atom is distributed in interstitial region. Is it correct for graphene?
>> I checked it for Diamond. The result was same!!!
>> 
>> If it is not correct How can i decrease the interstitial charges in my system. Is it possible?
>> 
>> I should mention that, for test calculation, i did SCF run for Iron Fe.
>> 
>> CTO  : TOTAL   INTERSTITIAL CHARGE=    1.0301020
>> TOTAL   CHARGE IN SPHERE  1 = 24.9698980
>> 
>> As you see the total charge in muffin-tin sphere is about 25 electrons.
>> 
>> 
>> Thank you very much for your help.
>> 
>> Best regards,
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>> 
>>  
> 
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