Formation of He Dimer in Nanotube Effect of Adsorption Potential

The effect of adsorption potential on the formation of a He dimer in a nanotube is systematically studied. This effect is characterized by two parameters, the effective radius <rho > and the effective width Delta rho. of the one-particle ground-state wave function of a He atom. The binding energy of a He-3 dimer exceeds 500 mK at 1.5 angstrom less than or similar to <rho > less than or similar to 2.0 angstrom and Delta rho less than or similar to 0.3 angstrom at strong adsorption potentials. For larger <rho >, the binding energy decreases as the adsorption potential increases. We also briefly discuss the magnitude of the binding energy of a He-3 dimer in the nanopores where a Fermi-liquid-like state of He-3 atoms is recently observed.