Crystal Builder

[Inaoton]

I tried building a ternary Semiconductor (ZnGa2Te4) using Crystal builder but I did not get the exact number of atoms in the unit cell of crystal structure of the ternary compound as given in the paper . I got a conventional unit cell containing 14 atoms while the unit cell in the paper contains 25 atoms. I find both total energy calculation and band-structure using GGA-PBE. The band gap is giving me accurate result  comparing with the experimental result but the total energy are very far away from that of the paper.Is this due to the number of atoms? Can a build the unit cell of 25 atoms? please help. I would highly appreciate your help. Thank you

[Anders Blom]

25 sounds wrong because your formula contains 7 units, but you'd need to provide more details (such as the paper reference, space group, Wyckoff positions, etc...).
You cannot compare absolute total energies between different calculations, as it depends on the pseudopotential and lots of other details.

[Aadhityan]

Try to repeat the same no. of atom and other parameters(such as cut-off energy, basis sets etc.). Then try your system. Band structure has directional property and also depending upon the number of atoms. For more about total energy and band structure check

https://www2.warwick.ac.uk/fac/sci/physics/current/postgraduate/regs/mpags/ex5/bandstructure/
 
www.matfys.lth.se/staff/Andreas.Wacker/Scripts/bandstructure_intro.pdf

[Inaoton]

Thank you  a lot both of you for your information.
Dear Anders Blom,
         ZnGa2Te4 bearing tetragonal structure has space group 82(I4bar). The atomic positions of the ZnGa2Te4 crystal are (Zn = 0, 0.5, 0.75; Ga = 0, 0, 0; Ga = 0, 0.5, 0.25; Te = 0.269, 0.242, 0.131). The optimized lattice parameters are a = b = 5.80 and c = 11.88. The reference paper is  (http://dx.doi.org/10.1016/j.materresbull.2016.10.012). I am not able to get the total 25 atoms in the structure. What could be the error? Could you please help..

[Ulrik G. Vej-Hansen]

It sounds very odd that it should have 25 atoms in the unit cell, when the formula unit is 7 atoms. Do you mean 28 instead of 25?

EDIT: I found the paper, and I am afraid that you are misreading the figure. There are indeed 25 atoms shown, but that is because they show all atoms on corners, edges and faces. The Ga atoms on the corners should only count 1/8 each, as they are shared between 8 different unit cells, and so on.