On the Lattice Dynamics of Solid Helium and Supersolidity

Abstract

In quest of a possible explanation of the recently revealed phenomena in solid 4He, 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 ≤0.2 A and by ∼0.6 A for the ground and excited states respectively at lowest densities in solid 4He. Our findings strongly correlate with recently revealed roton-like modes in solid 4He and are discussed in context of a facilitated delocalization and a glassy-like behavior in solid helium.