Static polarizabilities of Nan (n≤9) clusters:: An all-electron density functional study

This paper presents static polarizabilities and polarizability anisotropies of sodium clusters up to nine atoms calculated in the framework of density functional theory. The calculations of the static polarizabilities and polarizability anisotropies have been performed using a finite field approach implemented in the density functional program ALLCHEM. The calculations were of the all-electron type. Local and gradient-corrected exchange-correlation functionals have been used. All molecular geometries were fully optimized at both levels of theory. A vibrational analysis was performed in order to discriminate between minima and transition state structures on the potential energy surfaces. Equilibrium geometries, bond distances, harmonic frequencies, static polarizabilities, and polarizability anisotropies for sodium clusters up to the nonamer are presented. The obtained results are compared with experimental data as well as with other theoretical results. The calculated and experimental polarizabilities are in good agreement. For the trimer and the hexamer, the effect of different isomers in the calculation of the polarizability was investigated. This work demonstrates that the used approach allows the prediction of reliable electro-optical properties of metallic systems. (C) 1999 American Institute of Physics. [S0021-9606(99)30434-7].