The Debye-Waller factor and the mean-squared displacement from lattice sites for solid 3He and 4He were calculated with path-integral Monte Carlo at temperatures between 5 and 35 K, and densities between 38 and 67 nm-3. It was found that the mean-squared displacement exhibits finite-size scaling consistent with a crossover between the quantum and classical limits of N-2/3 and N-1/3, respectively. The temperature dependence appears to be T3, different than expected from harmonic theory. An anisotropic k4 term was also observed in the Debye-Waller factor, indicating the presence of non-Gaussian corrections to the density distribution around lattice sites. Our results, extrapolated to the thermodynamic limit, agree well with recent values from scattering experiments.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2000
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics