They say ZPE is the energy of the system at 0 K due to vibrations and even though the Schroedinger equation gives us the ground state minimum energy of the system (lets say by DFT/HF/QMC whatever), this energy is a little higher than that. My first question is, because I have learnt that SEqs is the most basic equation of QM, why are the atomic vibrations at 0 K not an out come of the SEqs. Because in reality now our ground state is redefined. If the system can NEVER have energy less than ZPE then isn't it the ground state energy. I know it might be very difficult to calculate, but apart from the electronic ground state shouldn't ZPE be also included in the ground state?? Or is this energy out of the purview of SEqns My second question is - if i am simulating (using DFT or other ab-initio method) the lattice system which has total integer spin (like lets say a collection of rubidium atoms) - then does my simulation actually give me a BOSE EINSTEIN condensate..??