[QE-users] Feo unit sell relax

[Ing. Martin Matas]

Dear Vishva,

Change ibrav from 2 to 1.

On the one hand, ibrav = 2 is a rhombohedron-shaped simulation cell, a primitive cell of the fcc structure. A rock-salt material contains 2 atoms in this cell.
On the other hand, your ATOMIC_POSITIONS correspond to an 8-atom conventional cube-formed cell of the fcc structure (ibrav = 1).
Hence, you describe four simulation cells instead of one, so many atoms overlap.

This can be easily found in the pw.x input description.

In addition, you will most probably need more k-points.

Regards,

Martin Matas
PhD graduate
University of West Bohemia
Czech Republic


 Středa, Květen 15, 2024 13:28 CEST, VISHVA JEET ANAND via users <users at lists.quantum-espresso.org> napsal:

> Dear Users
> I try to relax the FeO unit cell but I face a problem that is attached here
> in the output file and I also attached the input file.
> In the input file are no. of atoms right with ibrav value? In input i am
> using angstrom atomic position exactly at the same position as crystal.
> Please help to resolve this problem.
> 
> -- 
> With Regards
> Vishva Jeet Anand
> Research Scholar
> Department of Chemistry