[Wien] construction supercell

[Jorissen Kevin]

I have seen such things e.g. when I studied InGaN (people use a formula like
a[AlxInyGa1-x-yN] = (1 - x - y)aGaN + xaAlN + yaInN.
This sort of relation is known as 'Vegard's law'.  Of course it is itself an approximation, and then people invented parameters giving the deviation from Vegard's law ...)
I don't know for which systems such an approach is valid, and for which it is not.
 
I've seen something similar for TiO, when there is no real substitution but there are vacancies, and the lattice parameter relates to the Ti and O content.
 
As to whether you can use your experimental lattice constants for WIEN : it is always better to use *theoretical* lattice constants.  Of course, to determine these, the experimental values may be a good starting point, as you suggested yourself.
 
 
Kevin.
 
 

	-----Oorspronkelijk bericht----- 
	Van: Ercan Ucgun [mailto:ercanucgun at hotmail.com] 
	Verzonden: ma 11/10/2003 12:19 
	Aan: wien at zeus.theochem.tuwien.ac.at 
	CC: 
	Onderwerp: RE: [Wien] construction supercell
	
	

	Dear Kevin;
	You are saying that the lattice constant will be changed with 'x' parameter
	and that there are simple empirical laws giving a linear relation. Would you
	give me more information about these laws for example where can i find them.
	Also we have some experimental lattice constants for some concentrations. Is
	it possible to use this experimental ones in wien2k calculations and then
	try to find lowest enegy. Thanks in advance. Thank you Cottenier also.
	
	
	
	Yrd. Doc. Dr. Ercan UCGUN
	Dumlupinar Universitesi
	Fen Edebiyat Fakultesi
	Fizik Bolumu
	Kutahya / TURKEY
	
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