Self‐expansion and compression of charged clusters of stabilized jellium

Abstract

mIn a positively charged metallic cluster, surface tension tends to enhance the ionic density with respect to its bulk value, while surface-charge repulsion tends to reduce it. Using the stabilized jellium model, we examine the self-expansion and compression of positively charged clusters of simply metals. Quanta1 results from the Kohr-Sham equations using the local density approximation are compared with continuous results from the liquid drop model. The positive background is constrained to a spherical shape. Numerical results for the equilibrium radius and the elastic stiffness are presented for singly and doubly positively charged aluminum, sodium, and cesium clusters of 1-20 atoms. Self-expansion occurs for small charged clusters of sodium and cesium, but not of aluminum. The effect of the expansion or compression on the ionization energies is analyzed. For Al,, we also consider net charges greater than 2+. The results of the stabilized jellium model for self-compression are compared with those of other models, including the SAPS (spherical averaged pseudopotential model).Sons, Inc. @ 1996 John Wiley & lium model, the ions are replaced by a continuous charge background of density E = 3/(4n-r:), truncated sharply at a cluster radius R = r, N:l3, where No is the number of valence electrons in the neutral cluster. This model is widely used in the physics of metal clusters, since the precise position of the ions is not important for many physical properties. Stabilized jellium as well as jellium 1 . Introduction he stabilized jellium model (SJM) or struc-T tureless pseudopotential model 111 is a simple modification of the jellium model. In the ]el-