title: Seeing the atomic orbital: first-principles study of the effect of tip termination on atomic force microscopy.
abstract: We perform extensive first-principles calculations to simulate the topographical atomic-force-microscope image of an adatom on the Si(111)-(7 x 7) surface, demonstrating the feasibility of imaging not only the atoms but also the atomic orbitals. Our comparative study of tip terminations shows that two subatomic features can appear for a single adatom when it is imaged by a Si(001)-type tip having two dangling bonds on its apex, while only one feature would appear if it were imaged by a Si(111)-type tip having one dangling bond on the apex. The key condition for seeing the atomic orbitals is to bring the tip so close to the surface that the angular-dependent force dominates the tip-surface interaction.
authors.affiliation: Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Minghuang
authors.initials: M
authors.lastname: Huang
authors.forename: Martin
authors.initials: M
authors.lastname: Cuma
authors.forename: Feng
authors.initials: F
authors.lastname: Liu