Metastable solid⁴He and the possible role of point defects

The metastable phase of solid⁴He and the possible role of point defects in its destabilization are investigated by the introduction of a trial function of the shadow class with an explicit symmetrical kernel. This is a trial function that ensures the possible exchange of atoms and the delocalization of atoms and defects in a very effective manner. We show that the formation energy for vacancies is equal to zero at a pressure P_c=20±2 atm, which is in excellent agreement with the experimental observation. The pressure at which a self-interstitial also has a formation energy equal to zero, is in agreement with the density where vacancies have the same property. Formation energies of a³He interstitial or a substitutional impurity were estimated. Other properties of interest for systems made from⁴He atoms are estimated and compared with results from the literature whenever available.