Application of thin films method in the study of alkali–semiconductor interaction

The computation of atomic structure from first principles is a challenging theoretical endeavor. The complexity grows substantially when dealing with films and surfaces, because one can no longer exploit the three‐dimensional periodicity. Here we expound upon the self‐consistent field pseudopotential slab method with local density approximation to study thin films and ordered overlayers on surfaces. Plane wave basis sets are used because they are free from linear dependency problems due to their orthonormal properties. The results are illustrated by investigating the atomic structure of metal overlayers on the Si(001)‐2 × 1 surface at initial coverages. Major emphasis is on alkali metals, but Al is included for comparative purposes. The nature of the interaction and the role of Peierls distortions in metal–semiconductor energetics are presented. © 1992 John Wiley & Sons, Inc. Copyright © 1992 John Wiley & Sons, Inc.