Density Functional Finite Cluster Method for Polarizability of Large BeN Three-Dimensional Systems
Résumé
The structures and the properties of small clusters are known to be quite different from those of the bulk material. Consequently, the focus of most studies is towards understanding the changes in electronic properties with increasing cluster size. Linear static electronic dipole polarizabilities of the BeN (N → ∞) solid are obtained at the DFT(PWB91) level by extrapolation of ab initio calculations on BeN (N = 1, . . . , 132) clusters. For the mean polarizability, a [5s3p] basis set is shown to give accurate values if the tri-periodic clusters are big enough. No calculation has yet been carried out on BeN (N → ∞), but it is clear that these linear properties converge relatively slowly with cluster size. For BeN, cluster size up to N = 90 atoms are sufficient to give limiting infinite solid polarizabilities with relatively small uncertainties. For N = 132, the mean polarizability result is probably very accurate. These results suggest that DFT is a good method for the determination of these properties. © 2000 John Wiley & Sons, Inc.