# What Wyckoff position to put in Input file of Unit Cell of TiCoSb?

$$\ce{TiCoSb}$$ has Wyckoff position as

 Ti  Ti          0.25000    0.25000    0.25000    1.000    0.050    4c      -43m
Co  Co          0.00000    0.00000    0.00000    1.000    0.050    4a      -43m
Sb  Sb          0.75000    0.75000    0.75000    1.000    0.050    4d      -43m


I want to know the position of 4 Ti atoms, as I want to try to do basic calculation substituting each position of Ti for alloying.

I don't want to use supercell as that would increase time of calculations and I don't have that much capacity in my PC. Please help me to identify these positions.

I want to keep the number of atoms to no more than 6. My current understanding is that I have to remove symmetry to get to know these positions.

• What you want to calculate or find out is still not clear. For scf input file the position of all the atoms are correct it seems. materialsproject.org/materials/mp-5967. In a unit cell I believe there are three atoms and you have positioned them correctly. Dec 28, 2021 at 15:51
• @sslucifer I want to see the effect of doping at Ti site in order to see its effects on properties. So i need to confirm the position of atoms in order to replace them one by one. Dec 28, 2021 at 16:14

You can use the Bilbao Crystallographic Server. Then open (click) on the first menu Space-group symmetry and click on the WYCKPOS menu to go to the Wyckoff Positions of Space Groups.

There you put the space group number and the server will return the corresponding Wyckoff positions.

Just in between... Working with alloy demands supercell in order to obtain physically manful results. Only 6 atoms will return meaningless results.

https://www.cryst.ehu.es/cryst/get_wp.html

• Sir then how do I solve this because I don't have supercomputer. Is it possible to do so on 8 GB RAM with intel i7? The reason i am taking 6 atoms is because i found in a research paper that the authors took it and got output. Dec 28, 2021 at 16:17
• I've been there! You can use 6 atoms as a very simple approximation. The computational resources are directly bind to the system size and the software you will use. In my notebook (i7, 8 cores & 8GB RAM) with SIESTA I can work with around 100 atoms.
– Camps
Dec 28, 2021 at 16:24
• Thank you sir for helping out. I will try to do these calculations to see what I can do. As i don't have any expert in the computational field to help me with anything related to DFT at my campus. So i have been learning it on my own by reading stuff. I will try to see if I can find a computer here. If it's possible and you have time I would like to ask further problems regarding this. As I definitely want to learn DFT, do complete my masters thesis and would like to study it further at PhD level. Dec 28, 2021 at 16:32
• @epsilon02fft Camps is correct. If you are working with 6 atoms for such alloys, it will not give correct results. I suggest you find resources in your campus. I am not sure but if some professor are working with DFT or such calculations extensively, then they must have access to some cluster in campus or rent some cluster. You can ask them how to get access to it and if they are generous they can let you use some free time on it. Dec 28, 2021 at 17:15
• @sslucifer I have been trying. There is no luck yet. There is no professor who can help. How many atoms should i atleast try for this one? What do you suggest? I also have to complete with my thesis in next few months, so there is not much time i am afraid. Dec 28, 2021 at 17:25