THE STABILITY OF ASPERITIES ON W(001)

Instrumental as the electron sources in electron microscopes, the FIM, the STM, flat panel displays, and other technologies, sharp tungsten structures nevertheless remain for the most part unexamined on the ato mic scale. We have modeled a sharp tungsten asperity in order to inves tigate its stability, upon which these applications are critically dep endent. Using the extended embedded-atom method, we have determined th e energy barriers for several rearrangements which blunt the asperity. We also obtain the lowest-energy pathways for such rearrangements, an d these highlight the importance of directional bonding tendencies for elements from the center of the transition series. (C) 1997 Elsevier Science B.V.