Accuracy of Cluster Model Calculations for Quasicrystal Surface

Abstract

Accuracy of the adsorption energy on a quasicrystal surface calculated with the density functional theory and cluster models were discussed. Two types of cluster models of various sizes were tested to represent a fivefold surface of the Ag–In–Yb quasicrystal. Some cylindrical clusters caused unnaturally rippled potential energy surfaces regardless of the cluster thickness. However, it was confirmed that the ripples are disappeared with a cluster radius of 1.4 nm or larger. A similar trend was observed even in the hemispherical clusters, and also confirmed in their root mean square errors. It was concluded that both cluster models with a certain size are expected to give relative adsorption energy within an error of 0.15 eV.

Fig. 1 (a) Surface top layer of the icosahedral Ag–In–Yb quasicrystal. The red and green spheres denote In and Yb atoms. (b) The shaded area in (a). Red arrow indicates a region used for calculations.