The Study On Stable Structure Of Clusters Based On Model Potential And Density Functional Theory

Clusters have attracted extensive attention due to their unique physical and chemical properties,and have become one of the hot research topics in condensed matter physics,materials and other scientific fields.The number of local minimum values on the potential energy surface is very large and the configuration of clusters increases exponentially with the size of clusters,so it is very difficult to optimize the structure of clusters.Using model potential and density functional theory as a theoretical method,we explore the regularity of the stability structure of clusters in terms of structure and properties.Its main contents are as follows:1.Structural optimization of quaternary Ag–Au–Pd–Pt clusters up to 38 atoms is performed using adaptive immune optimization algorithm and the Gupta many-body potential.By fixing the atomic number of three types and varying the number of one type in quaternary clusters,geometrical effects by different types of noble metals are investigated.Results show that most configurations present the growth pattern based on the 19-atom double icosahedra.Furthermore,the order parameter indicates that in quaternary clusters Ag and Au atoms mainly occupy the surface sites,Pd atoms tend to be in the middle shell,and the inner shell is located by Pt atoms.The study of the number of bonds indicates that Ag and Au atoms prefer scattering and forming a circle on the surface,respectively.2.Potential energy surfaces?PES?of Co clusters with Gupta potential using four parameter sets are characterized in terms of conformational analysis.Their structures are obtained using three optimization algorithms.Three new structures with lower energies for one of these parameter sets are found.For all parameter sets,the structural variation from icosahedron to decahedron to close-packed face centered cubic?FCC?or stacking fault FCC and amorphous motifs is related to the potential range of the parameters.The difference between the PES is investigated,and for a long potential-range parameter,the number of local minima on the PES is extremely large.3 The geometric structures and relative properties of Co₂B_n clusters up to n=8weresystematicallyinvestigatedbyusingdensityfunctionaltheoryat B3LYP/6-311+G?d?//B3LYP/6-31G?d?level.The binding energies per atom,the second-order differences of energies,HOMO-LUMO energy gaps,vertical electron affinities,vertical ionization potentials and chemical hardnesses of these clusters show that Co₂B₇ cluster has the characteristics of magic number.