Comparison of MNDO to tight‐binding, total‐energy methods for surface atomic structure determination: Aluminum phosphide (110)

Tight‐binding, total‐energy ( TBTE ) models have been successfully used to calculate the equilibrium surface atomic structures of a variety of materials, but are difficult to apply to substances with complicated interatomic repulsions. In these cases, the modified neglect of diatomic overlap ( MNDO ) method, which specifically includes longer‐range interactions, may provide an effective alternative. We present new calculations of the surface atomic structure of the AlP (110) surface using both techniques. This surface, whose structure has been determined quantitatively using a low‐energy, electron‐diffraction intensity analysis, displays a well‐known relaxation characteristic of (110) surfaces of zincblende‐structure semiconductors. The TBTE model, parameterized to bulk AlP properties, provides a more accurate prediction of the relaxed surface atomic positions, although MNDO , parameterized to small molecules, produces acceptable results. Despite the greater demands placed by MNDO on computer resources, it may prove useful in the study of materials that are difficult to model within a TBTE framework. © 1992 John Wiley & Sons, Inc.