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## Creating an amorphous HfO2 supercell on ABINIT

Total energy, DFT+U, BigDFT,...

Mohamedy002
Posts: 9
Joined: Wed Aug 10, 2016 10:56 am

### Creating an amorphous HfO2 supercell on ABINIT

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 (67.2 KiB) Viewed 1463 times
Last edited by Mohamedy002 on Tue Aug 30, 2016 7:45 pm, edited 2 times in total.

Mohamedy002
Posts: 9
Joined: Wed Aug 10, 2016 10:56 am

### Re: Creating an amorphous HfO2 supercell on ABINIT

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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Thanks,
Hassan

Mohamedy002
Posts: 9
Joined: Wed Aug 10, 2016 10:56 am

### Re: Creating an amorphous HfO2 supercell on ABINIT

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 (35.68 KiB) Viewed 1453 times

Mohamedy002
Posts: 9
Joined: Wed Aug 10, 2016 10:56 am

### Re: Creating an amorphous HfO2 supercell on ABINIT

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 (31.58 KiB) Viewed 1447 times