Normally for ZnO, ibrav = 4 (i.e hexagonal). Now I want to perform gas sensing studies. So I create a vacuum of 10A in nanolabo where the atoms are placed. The ibrav now changes to 12 (i.e monoclinic) when I update.My doubts are:
1. Is it ok to go ahead with the calculation with ibrav = 12?
2. Why exactly does this happen?
3. If this is not ok, then how do I make the input file with ibrav = 4?