VARIATIONAL CALCULATIONS IN A HALF-SPACE FOR THE INTERACTION OF A GROUND AND EXCITED-STATE HELIUM ATOM WITH ITS MIRROR-IMAGE

Correlated trial wave-functions (depending explicitly upon the inter-e lectronic separation in the helium atom) subjected to boundary conditi ons excluding the helium electrons from the solid surface are used in half space, to evaluate in a variational approach the holding potentia l between an helium atom in its ground and metastable S-3 State with a perfectly imaging metallic conductor limited by a plane surface. Inte r-electronic correlation effects are pointed out, and are seen to be n on negligible. The holding potential for the helium S-3 displays a wel l of nearly an order of magnitude deeper than for the ground state. Th ese results could be useful to determine the distance of closest appro ach of thermal atoms, and an approximate wave function for an helium a tom interacting with a surface.