Characterization of Zero-point Vibration in One-Component Crystals
  We study the magnitude of zero-point vibration in one-component crystals. For the crystals whose constituent atoms share the same bonding geometry, we prove the existence of a characteristic temperature, T0, at which the magnitude of zero-point vibrations equals to that of the excited vibrations. Within the Debye model T0 is found to be ~1/3 of the Debye temperature. The results are demonstrated in realistic systems. 
Yong Yang and Yoshiyuki Kawazoe
cond-mat.stat-mech cond-mat.mtrl-sci quant-ph