I am trying to duplicate the results of this [study](https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.8b08449) using VASP. Where they have observed that the structure of $Cs_2SnI_6$ switches from Fm-3m to I2/m upon application of pressure more than 3.3 GPa. They have also validated there experimental results using DFT but for that they have calculated the energy of various possible space groups and found that I2/m has lesser energy as compared to Fm-3m above 3.3 GPa. I want to do this using Geometry relaxation directly. 

Directly running geometry relaxation with Pressure does not work because VASP maintains the symmetry. I also tried running with `ISYM=0` that did not help either. 

Another idea is to distort the structure manually as has been done [here](https://mattermodeling.stackexchange.com/questions/1597/dealing-with-symmetry-of-ordered-primitive-cell-during-dft-structure-relaxation) but this switches the symmetry from Fm-3m to let's say some X symmetry.Now this X symmetry is maintained even through the geometry relaxation. 

What do you think is the best method to solve this issue ??