1. Introduction Bloch’s theorem and translational symmetry are two of the main bricks in the foundation of solid state physics. Their use in crystal lattices makes an implicit assumption, not emphasized in the texts we are aware of. Bloch’s theorem is mathematically correct of course for a fixed, periodic potential, but real nuclei move under the influence of thermal fluctuations, so that they have random configuration without translational symmetry at any moment in time.
