Yes, you have to use supercells.
In fact, you even have to use pretty large supercells, since you want to
simulate low "x" and even for "large x" one should always use LARGE
supercells and put in some DISORDER.
If one wants to simulate a 50:50 ALLOY, one cannot use just a 2-atom
cell AB (since this corresponds to a "compound", but NOT an ALLOY).
An alloy is DISORDERED and you need to simulate that by some random
distribution of the atoms in a supercell which should be as large as
possible.
On 09/22/2013 06:49 AM, Kondaiah Samudrala wrote:
Dear all,
Presently, I am working on the DFT calculations for AB2 type layered
materials and up to now I exactly reproduced the experimental values.
Now, I want to change the occupancy of B atom from B2 to B(2-x), here
x=0.0, 0.05, 0.1, 0.15,0.25... and predict the electronic properties of
the same compound.
But, I am little confuse with the calculations. i.e. Whether I have to
use super cells or normal unit cell for occupied AB(2-x) structures????
I hope a positive reply..
with regards
Appalakondaiah Samudrala
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