[Pw_forum] Graphene doped relaxation

[David Foster]

Dear Users
I have done following steps for optimization of Ni- doped 3*3 graphene supercell:

1- I constructed unit cell of graphene monolayer (2 atoms) with large vacuum (20A in z direction).
2- I optimized both atoms positions and lattice parameters (except for z). It means a,b, alpha,beta, and gamma might be changed during relaxation.
3- Then I constructed 3*3 supercell by optimized data of unit cell
4- After, I substituted one Ni atom in place of one carbon atom.
5-  I optimized again both atoms positions and lattice parameters (except for z). It means a,b, alpha, beta, and gamma might be changed during relaxation.

Is this process right? especially for step 5. In other words, do I need to relax lattice parameters (except z) in addition to atoms positions or not?

Regards
 
 David Foster
 
 Ph.D. Student of Chemistry