Structural And Electronic Properties Of MB_n (M=Cr, Mn, Fe, Co, Ni, N≤7) And MB_n (M=Y, Zr, Nb, Mo, Ru, N≤10) Clusters By Density Functional Theory

This dissertation is devoted to study the structure and electronic properties of 3d and 4d transition metal doped MBn clusters using first-principles density functional theory (DFT) with generalized gradient approximation. The main content is as follows:In the first place, we give a brief introduction to clusters. Firstly, we introduce the category and research meaning of clusters. We also give a simple introduction of the review of the studies having done on clusters. Secondly, we introduce the basic conception of clusters. Then, we simply describe the purpose and results of our work on clusters.Next, we introduce the basic concept and progress of DFT. Development of quantum chemistry promotes the establishment of DFT. Thomas-Fermi model is the first theory using density of electrons as the main variable.Theorem of Hohenberg-Kohn is the fundament of DFT and is developed to Kohn-Sham equation, which can be used to perform real calculations. Now, new corrections and extensions, together with developed exchange-correlation functionals, have made DFT more accurate and suitable for more systems. At the end of this chapter, we introduce the DMOL3 Software.In the end, we have investigated the stability, electronic, and magnetic properties of transition metal doped MBn (M=Cr,Mn,Fe,Co,Ni n≤7) and MBn (M= Y,Zr,Nb,Mo,Ru n≤10) clusters using first-principles density functional theory (DFT) with generalized gradient approximation (GGA). The equilibrium structures of MBn(M=Cr,Mn,Fe,Co,Ni n≤7) and MBn (M= Y,Zr,Nb,Mo,Ru n≤10) clusters are generally consistent, though the computational results of magnetic moment between are difference. Charge transfers from M atom to B atoms. The relative orientation between the magnetic moments of the M atom and those of its neighboring B atoms mainly exhibits an antiferromagnetic alignment for CrBn,MnBn and FeBn, while it mainly shows a ferromagnetic alignment for CoBn and NiBn clusters. The magnetic moment on the transition metal atom is generally smaller than the total moment except for ZrB3,NbB2,MoB2,MoB7,RuB and RuB5, and this rusult is different from our former computational results for MBn (M = Cr,Mn,Fe) clusters.