Ground states of weakly bound three-atom systems: energies and shapes of (He2X)-He-4 clusters from Monte Carlo calculations

摘要

The interactions between alkali atoms and He-4, as well as those between H- and He-4, are known to be even weaker than those between two helium atoms. In this work we show that when the three-particle potential energy surface is obtained as a sum of two-body functions, the ensuing ground state configurations are indeed very weakly bound and acquire spatial shapes difficult to describe in simple configurational terms. We have employed the quantum diffusion Monte Carlo method to analyse the He2Li, He2Na and He2H- systems, for which possible molecular 'shapes' are extracted from the final DMC distributions by defining within them conventional chemical structures with varying degree of 'stiffness' attached to the nuclear positions. [References: 38]