M_nga (m = Cu, Ag, Au; N = 1-6) Density Functional Theory Study Of The Geometric Structure Of Small Clusters Of Binary Alloys, Stability And Electronic Properties

Coinage metal alloy clusters are widely used in luminescence, photosensitive and special functional materials. Recently a few experimental studies of coinage metal clusters with gallium have been reported. To our knowledge, few theoretical works for them have been found.In this paper, the coinage metal alloy clusters MnGa(M=Cu, Ag, Au; n=1-6) are studied theoretically by Hartree-Fock method (HF), second-order M?ller-Plesset perturbation theory (MP2), coupled cluster formalism restricted to single and double excitations including a perturbative estimate for triples (CCSD(T)) and densty functional theory (DFT) B3LYP of quantum-mechanical ab initio calculation with Gaussian98W program package.Firstly, the ground electronic state and reasonable dissociation limits are correctly determined based on Atomic and Molecular Reaction Statics and the Group Theory. The small coinage-metal gallium compounds M2Ga(M=Cu, Ag , Au) are studied. It is found that the bend structure with C2V symmetry for M2Ga(M=Cu, Ag , Au) is more stable than the linear structures and the cluster of Au2Ga is the most stable cluster. The binding energies are evaluated, which indicate that doping clusters M2Ga are more stable than the pure clusters M3. Moreover, the vibrational frequencies of the ground state structures are calculated. The electron correlation effects are investigated, which compact and stabilize the present species.It's the first time to use the B3LYP method of density function theory to research the stability of the ground state structures of clusters MnGa(M=Ag, Cu, Au; n=1-6), the binding energies per atom, the highest occupied molecular orbital energy levels, the lowest unoccupied molecular orbital energy levels, the energy gaps, the electron affinities and the ionization potentials and so on, systematically. The results of caculation show that the doping clusters MnGa(M=Ag, Cu, Au; n=1-6) are more stable than the pure clusters Mn(M=Ag, Cu, Au; n=2-7). The research results indicate that the"odd-even"alternations and"magic number"effect exist in all of them. Presence of odd-even oscillation effect of the values are firmly correlate to electron-pair effect. And Ag5Ga, Cu5Ga cluster are more stable than others and have"magic number"effect. According to the change of energy levels and HOMO-LUMO gaps, choosing different adulteration style provides theoretical reliance for new materials design with various natures.Finally, the infrared spectrums of all the ground states are presented in detail, which is helpful in understanding of their structures. And it is expected that the results can be useful for experimental study.