Few helium atoms in quasi two-dimensional space

摘要

Two, three and four He-3 and He-4 atoms in quasi two-dimensional space above graphite and cesium surfaces and in "harmonic" potential perpendicular to the surface have been studied. Using some previously examined variational wave functions and the Diffusion Monte Carlo procedure, it has been shown that all molecules: dimers, trimers and tetramers, are bound more strongly than in pure two- and three-dimensional space. The enhancement of binding with respect to unrestricted space is more pronounced on cesium than on graphite. Furthermore, for He-3(3) (He-3(4)) on all studied surfaces, there is an indication that the configuration of a dimer and a "free" particle (two dimers) may be equivalently established. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 12]