Hello every one

Please, I would like your guidance. When performing  my calculations for electronic band structures, I made my structure P1 while doping it with another molecule. I would like to have the symmetry (not P1) after the geometry optimization. How is it possible to convert a P1 to a symmetry (or to apply symmetry) during geometry optimization? Is there any workflow (any Module is okay) or recommandation I can get from you?

To be more clear, this is what I did:

1; Downloaded a cif file as a basis

2; Made it P1

3; Doped with the new molecule; Namely I deleted one full molecule and replaced it with the new one before adjusting the positions of all the molecules as they chansged their initial positions when I was manipulating

4; Ran the geometry optimization with CASTEP

5; At the end of the Geometry Optimization, I realize that it is still P1, and the positions of the molecules are very different from the initial structure, some have even been totally removed

P. S: The goal is to see up to which concentration of the doping molecule, the structure changes the symmetry.

Thank you in advance for your support