Normal and Superfluid Helium


We used the FBSD methodology, with path integral treatment of the density (including identical particle exchange), to calculate the single-particle velocity autocorrelation function and the incoherent structure factor of 4He in the neighborhood of the lambda transition. This work was the first successful simulation of superfluid helium dynamics. The FBSD results in the intermediate to high momentum transfer regime were in remarkably good agreement with those obtained through inelastic neutron scattering experiments, both above and below the transition temperature. By comparing the FBSD results to those obtained in the absence of particle exchange operations, we were able to prove definitively that the observed peak enhancement observed in the superfluid regime arises mostly from quantum statistical effects, thereby illustrating the role of Bose-Einstein condensation on the kinetic properties of superfluid helium.

Related Articles:

A. Nakayama and N. Makri, “Simulation of dynamical properties of normal and superfluid helium”, Proc. Nat. Acad. Sci. U.S.A. 102, 4230-4234 (2005).

N. Makri, A. Nakayama and N. J. Wright, “Forward-backward semiclassical simulation of dynamical properties in liquids”, invited review, J. Theor. Comp. Chem. 3, 391-417 (2004).