Density functional finite cluster method for polarizability of large Be-N three-dimensional systems

The structures and the properties of small clusters are known to be quite d ifferent from those of the bulk material. Consequently, the focus of most s tudies is towards understanding the changes in electronic properties with i ncreasing cluster size. Linear static electronic dipole polarizabilities of the Be-N (N --> infinity) solid are obtained at the DET(PWB91) level by ex trapolation of ab initio calculations on BeN (N = 1,...,132)clusters. For t he 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 c arried out on BeN (N --> oo), 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. (C) 2000 John Wiley & Son s, Inc.