One of the challenges of modelling completely new material using DFT is the selection of initial geometry. Usually, an experimental structure (cif) which appears to be similar to the new material in question is selected intuitively (correct me if I'm wrong) and several such selections are made to comparatively analyse the optimised free-energies if necessary. I found a similar question that concludes optimised geometry depends heavily on the initial geometry.
Let us assume the full relaxation of ionic positions, cell volume and cell shape is carried out starting from some geometry.
My question is, is there a possibility to change the initial crystal system during relaxation? Can it change from orthorhombic to cubic, tetragonal etc., for example, in the process of finding a local minimum in the potential energy surface?
If it does not change even after the relaxation, does that mean the selected initial geometry is a good starting point?