Theoretical Study of Quantum Gel Formation in Superfluid ⁴He

Abstract

Bosonic density functional theory calculations were carried out for neon, argon, and fluorine based systems in superfluid ⁴He with an emphasis on the formation of dimeric species in the liquid. These atomic species display relatively strong binding with helium and hence their solvation structures in the liquid exhibit highly localized liquid helium layers around them. These solvent layers modify the gas phase dimer potentials by inclusion of a recombination barrier, which provides stabilization for the solvated atoms. Of closed shell species neon is shown to exhibit a recombination barrier of 3 K for the dimer and up to 5.8 K for specific cluster geometries. For argon, the liquid induced potential barrier is only 0.7 K and it has a rather large amount of excess energy available along the recombination coordinate indicating that it is not possible to stabilize argon atoms in superfluid helium. Atomic fluorine shows the most pronounced effect with the recombination barrier of 26.8 K for producing ground state F₂. It is concluded that neon and fluorine atoms are good candidates to form impurity based quantum gels in bulk superfluid helium.