Creating an amorphous HfO2 supercell on ABINIT

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Creating an amorphous HfO2 supercell on ABINIT

Postby Mohamedy002 » Tue Aug 30, 2016 2:40 pm

Please I would like to have some hints about how to create an amorphous HfO2 supercell. BTW I am beginner to ABINIT.
I think I will approach the problem through the following steps:
First, create a unit cell of HfO2.
Then, preform ground energy calculations (make convergence on both the acell and ecut values in order to achieve the minimum total energy)
After that, make a super cell of the unit cell by repeating it in x , y , and z? I do not have any knowledge about how this is done!
Then, go preform ground energy calculations again to achieve minimum ground state energy of this super cell

About amorphous I can not understand what does it mean. BTW I think by having a super cell of HfO2 then its then amorphous (Not sure but thinking).

Please kindly help with any hint or information.


Actually I know that HfO2 has three phases which are: a) cubic, b) tetragonal, c) monoclinic.

The cubic HfO2 structure is something like that the attached image.


Thanks,
Hassan
Attachments
Cubic HfO2.png
Cubic HfO2.png (67.2 KiB) Viewed 1359 times
Last edited by Mohamedy002 on Tue Aug 30, 2016 7:45 pm, edited 2 times in total.
Mohamedy002
 
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Re: Creating an amorphous HfO2 supercell on ABINIT

Postby Mohamedy002 » Tue Aug 30, 2016 3:45 pm

I think if I am going to work on the cubic phase of the HfO2 then the unit cell will consist of three atoms which are Hf of atomic number 72, and the other 2 are oxygen atoms of atomic number 8. Also the atomic position will be defined by the xred variable in ABINIT something like that:
xred
0.0 0.0 0.0
1/4 1/4 1/4
3/4 3/4 3/4

Please correct me if I am going the wrong path.
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.
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Thanks,
Hassan
Mohamedy002
 
Posts: 9
Joined: Wed Aug 10, 2016 10:56 am

Re: Creating an amorphous HfO2 supercell on ABINIT

Postby Mohamedy002 » Tue Aug 30, 2016 6:32 pm

I think first I should do convergence on both the values of ecut and acell

I did convergence on ecut (attached the convergence curve)

The converged ecut value is 80 Ha

BTW I found that the converged total energy value is -82.36 Ha ! (Actually this quite a big value)

Please if anybody could help am I doing the correct steps or not?
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Thanks,
Hassan
Attachments
Convergence Curve.png
Convergence Curve.png (35.68 KiB) Viewed 1349 times
Mohamedy002
 
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Re: Creating an amorphous HfO2 supercell on ABINIT

Postby Mohamedy002 » Tue Aug 30, 2016 10:21 pm

I think I managed to create the unit cell of cubic HfO2 (attached the band structure). Actually I am not quite sure this is the correct band structure as it gives bandgap value (3.8eV) much greater than the theoretical value 3.6eV. How could I fix this band structure?

Also, please any hint about how to create a super cell of the amorphous HfO2.
As I knew that amorphous HfO2 mean super cell of HfO2 (i.e. breaking the periodicity of the crystal structure).
Is that correct?
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Thanks,
Hassan.
Attachments
HfO2 Band Structure.png
HfO2 Band Structure.png (31.58 KiB) Viewed 1343 times
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