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QuantumATK => General Questions and Answers => Topic started by: Inaoton on April 10, 2017, 17:01

Title: Building Crystal Structures with atoms at same positions
Post by: Inaoton on April 10, 2017, 17:01

Hello
         How can i build a crystal with atoms having same Wyckoff positions but different site occupancy factors? So with different occupancy factors they do not overlap .e.g a compound like AB2O4 having a Rocksalt structure.
 

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Anders Blom on April 10, 2017, 18:40

In this case you have also to consider the computational aspect, meaning that you need to create a large supercell, because that is what such a fractional occupancy actually means. However, the procedure is fairly simple. Build the structure with only one type of atom in each Wyckoff position. Then make a large supercell, and use the "alloy" tools in the Builder, in the right-hand panel under "Builders", to randomly replace the relevant percentage of atoms. Another alternative is to use the VCA method, as described in http://docs.quantumwise.com/tutorials/effective_band_structure/effective_band_structure.html

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Inaoton on April 11, 2017, 06:53

Thank you Sir

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Inaoton on January 16, 2018, 08:15

Quote from: Anders Blom on April 10, 2017, 18:40

In this case you have also to consider the computational aspect, meaning that you need to create a large supercell, because that is what such a fractional occupancy actually means. However, the procedure is fairly simple. Build the structure with only one type of atom in each Wyckoff position. Then make a large supercell, and use the "alloy" tools in the Builder, in the right-hand panel under "Builders", to randomly replace the relevant percentage of atoms. Another alternative is to use the VCA method, as described in http://docs.quantumwise.com/tutorials/effective_band_structure/effective_band_structure.html

Could you please provide me references of the same???

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Petr Khomyakov on January 18, 2018, 09:30

What do you mean by "references of the same"?

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Inaoton on January 18, 2018, 10:19

Thank you for reply.
 By Reference, I mean the reference papers for modelling of disordered structures (with fractional occupancy) where the same procedure (as quoted above ) is mentioned.

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Anders Blom on January 19, 2018, 09:35

Cf. https://arxiv.org/abs/cond-mat/9908364 and references 1-12 therein

Title: Re: Building Crystal Structures with atoms at same positions
Post by: Inaoton on January 19, 2018, 10:58

Thank you sir for your reply..