Structures and Properties of Core–Shell B@Mn₈@Mg₁₀ Cluster and Brief of Efficient Core–Shell Cluster Algorithm and Global Minima Algorithm Based on a Sequential Microdisplacement Press–Expand Method

Abstract

We present a sequential microdisplacement press–expand method. On this basis, we develop an efficient core–shell cluster algorithm with a given core-cluster structure from the arbitrary initial shell-cluster structure and further develop a global minima algorithm from the arbitrary initial structure. Many tests of stable clusters reveal that the structure of the stable core–shell clusters is an optimal atomic distribution of the outer atoms according to the potential fields of the core cluster. On this basis, we identify a new core–shell A@B8@C10 cluster. Applying a spin-polarized density functional theory (DFT) approach, we investigate the structural stability and magnetic properties of a B@Mn8@Mg10 cluster, which has high stability because of the strong p–d hybridization between B and Mn atoms and the strong s–d hybridization between Mn and Mg atoms. The most stable state is one in which the interface layer (Mn) atoms have an axial paramagnetic moment, whereas the Mn atoms have large local magnetic moments that are in reverse orientation to the magnetic moment orientations of the inner layer (B) atoms and the external layer (Mg) atoms. Using the B@Mn8@Mg10 cluster as the structural element, we design Mg2B N–1(Mn4Mg4) N (N = 2–8) nanochains when Mn atoms have an axial paramagnetic moment that remains in geometrical symmetry after DFT calculations. Moreover, the total magnetic moments of the nanochains increases linearly with the structural element N.