Self-localized electron state in a dense helium gas: Variational and self-consistent approaches

Using the variational and self-consistent approaches, the possibility of the formation of a self-localized polaronic state of an electron in a helium vapor under an increase in its density with increasing temperature is studied. It is shown that such a state arises when the temperature reaches a certain characteristic value. It has been established that, when the trial wave function of a localized electron is chosen in the form of a Gaussian distribution, the procedure for minimizing the free energy of the system leads to a self-localized state formation temperature close to that at which a sharp drop in the charge mobility with increasing temperature is experimentally recorded. It is shown that the application of a self-consistent approach based on the joint solution of the wave equation for an electron and the equation for the density of the surrounding vapor leads to qualitatively the same results as the variational method, although with a higher polaronic state formation temperature. Published under an exclusive license by AIP Publishing.