title: Equilibrium geometries and associated energetic properties of mixed metal-silicon clusters from global optimization.
abstract: The structural properties of the cluster series Me(m)Si(7-m) (Me = Cu and Li, m < or = 6) are studied by density functional theory (DFT) employing a plane wave basis. The equilibrium geometries and energetic properties of these clusters are obtained by use of the simulated annealing procedure in conjunction with the Nosé thermostat algorithm. The lowest energy isomer thus obtained is analyzed by density functional theory at the B3LYP/6-311+G(d,p) level including all electrons. Pentagonal ground state structures derived from the D(5)(h) equilibrium geometries of both Si(7) and Cu(7) are obtained for Cu(m)Si(7-m) with m < 6. The Li(m)Si(7-m) clusters, in contrast, tend toward adsorption geometries where m Li atoms are attached to a Si(7-m)framework with pronounced negative charge. For both Li(m)Si(7-m) and Cu(m)Si(7-m), a marked decrease of the energy gap is found as the number of metal atom constituents increases.
authors.affiliation: Computational Center for Molecular Structure and Interactions, Department of Physics, Atmospheric Sciences, Jackson State University, Mississippi 39217, USA.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wu
authors.forename: Frank
authors.initials: F
authors.lastname: Hagelberg
mesh_terms: D000465:Algorithms; D003300:Copper / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D012825:Silicon / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003300:Copper; D008094:Lithium; D012825:Silicon