Comparing the Stabilities of Nanoclusters and Cluster-based Materials: Alkali Halides and the First Row Element Compounds

摘要

We present state-of-the-art plane wave periodic density functional (DF) calculations aimed to unravel the structure and electronic properties of polymorphs of LiF, BeO, BN and C obtained by assembling LiF_(12), BeO_(12), BN_(12) and C_(24)C_(12) building blocks with cage structure. Specifically, a nanoporous analogue of the sodalite zeolite (SOD) structure can be obtained in this way. The energy difference between the ground state phases and the SOD bulk polymorphs (per LiF, BeO, BN or C_2 unit; hereafter referred to simply as unit) was found to increase across the LiF, BeO, BN and C series with ΔE_(SOD-atab) = 0.05,0.17,0.68 and 1.07 eV/unit, respectively. The different electron distribution on each cluster is illustrated by the ELF analysis. The electronic properties results demonstrate that the cage-based polymorphs of these materials have band gaps significantly different from those in the most stable state phase, which could be interesting for nanotechnology applications.