Hello all..
My question is regarding the size of a supercell for doping studies through DFT calculations..
Actually, I am dealing with a mono-layer and wish to see the effect of doping. For that, I checked 2*2 (a=14 and b= 18 A) and 3*3 (a=24 and b= 34 A) supercells, but to my surprise, both are showing different characters!! I mean one of them is semiconducting while the other one is conducting! Is it possible?
All I knew is, taking supercell is just a way to make the interaction of doped atom negligible, or in other words... to take the small concentration of dopants into account.. But changing the size should not alter the physical properties...
and If I am wrong and it actually changes the characters...What should be the reason behind it... and Then how should I decide which one I should go with??
Thanks in advance.
Looking forward for the assistance soon :-)
Supercells can be any size – large or small, low or high topped. They usually produce copious amounts of hail, torrential rainfall, strong winds, and substantial downbursts. Supercells are one of the few types of clouds that typically spawn tornadoes within the mesocyclone, although only 30% or fewer do so.
Dear Maya Kaur ,
With the limited information available in the question, let me provide some information.
In general, you resort to supercell in order to simulate defective structures. But, in this case, since you are simulating a monolayer compound, please check the correctness of the structure first. Simply be making supercells of a bulk unit cell does not make it a monolayer structure of the same compound.
Regarding the strange behavior of calculated properties, it would be really helpful if you can provide some more information regarding the structure and computational set up.
This depends upon two factors:
1. level of doping you want
2. Computational power
for example of you want to do doping of 12.5% of SIlicon in Carbon.
So if you are having a Carbon with one atom then you have to create supercell of 2*2*2 which will contain 8 atoms anf hence you can do the doping accordingly.
For doping ratio of 1/64 you have to create 4*4*4 supercell of Carbon.
I hope you got the point Maya Kaur
Hello Mr. Sruthil Lal S B,
Thank you very much for your answer.
Actually, I've cut a monolayer first (using SLABCUT keyword in CRYSTAL code) , and then tried to go for the supercell configurations for doping purposes...
Regarding computational details, I am using CRYSTAL code and applying B3PW potential to get the calculations done. Please let me know what other details should be shared...
Hello Abhinav Nag
Thank you very much for the response! I think I am getting your point.. and changing the concentration of dopants should obviously change the properties accordingly..
But still, my confusion is do changing the size or I should say just multiplying the cells do alter physical properties so drastically??? What if I do not want to perform doping...and wanna study the effect of size only...
All I knew was that multiplying the size gonna just multiply the total energy (?)
Am I doing some mistake (?)
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