Dr. Vitor Pedroso (Dept Physics, RHUL)

The metastable phase of solid 4He and the possible role of point defects in its destabilization are investigated by introducing a trial function of the shadow class with an explicit symmetrical kernel. This trial function ensures the possible exchange of atoms and the delocalization of atoms and defects in a very effective manner. We show that the formation energies for a vacancy or a self-interstitial are zero at a pressure of 20(2) atm, which is in excellent agreement with the experimental observation for the destabilization of the metastable solid. Properties of an interstitial or substitutional 3He impurity are also studied.

Fig. caption:  Vacancy formation energy versus crystal density. The red squares represent the variational results obtained by the shadow wave function with a symmetric kernel. Data from the literature are also shown for comparison. The dashed line is a quadratic fit of our results.