I began with an imported a .cif file from materials project and have updated the structure to my specifications. I would like to change the global cartesian coordinate system so that I can project the bands and DOS onto d-orbitals of a particular orientation.
To this end, I have determined the required 3D rotation matrix to transform from the original coordinate system to the new one. I have applied the transformation to the a, b, and c vectors given in the POSCAR file that define the unit cell. Specifically, I manually replace the coordinates that define the a, b, and c vectors by their transformed coordinates in the POSCAR file.
To check that the transformation had the desired effect, I open the modified POSCAR file in VESTA. The structure appears unchanged, but I expected the x,y,z coordinates of each atom to have changed according to the transformation. Instead, I find them to be exactly the same. Furthermore, if I try to export data from this modified POSCAR file, VESTA outputs a POSCAR with the original a,b, and c coordinates. It is as though VESTA has overwritten or ignored my modifications.
What is going on here? Is there another approach to change coordinates?