On the Lattice Dynamics of Solid Helium and Supersolidity

In quest of a possible explanation of the recently revealed phenomena in solid (4)He, which are ascribed to 'supersolidity', we reconsider the work of Nosanow and Shaw (Phys. Rev. 128:546, 1962) and calculate the ground-state and newly introduced excited state energies, the effective potentials and the Debye temperatures as functions of density within a Hartree approach. The wave functions were revealed to be not exactly localized at lattice sites but shifted aside by a parts per thousand currency sign0.2 and by similar to 0.6 for the ground and excited states respectively at lowest densities in solid (4)He. Our findings strongly correlate with recently revealed roton-like modes in solid (4)He and are discussed in context of a facilitated delocalization and a glassy-like behavior in solid helium.