Quantum Monte Carlo Simulations of Solid ~4He

摘要

Recent experimental investigations of solid ~4He have been interpreted as showing possible superfluidity in the solid at low tempera-tures, below 0.2 K. A solid behaving this way, exhibiting both long range translational order and superfluidity, has been called a supersolid phase. The existence of a supersolid phase was proposed many years ago, and has been discussed theoretically. In this paper we review simulations of the solid state of bulk ~4He at or near absolute zero temperature by quantum Monte Carlo techniques. The techniques considered are variational calculations at zero temperature which use traditional Bijl-Dingle-Jastrow wavefunctions or more recently, shadow wavefunctions; Green's function Monte Carlo calculations at zero temperature; diffusion Monte Carlo, and finally, the finite temperature path integral Monte Carlo method. A brief introduction to the technique will be given followed by a discussion of the simulation results with respect to solid helium.