Self-consistent field tight-binding model for neutral and(multi-)charged carbon clusters

摘要

A semiempirical model for carbon clusters modeling is presented,along with structural and dynamical applications.The model is a tight-binding scheme with additional one-and two-center distance-dependent electrostatic interactions treated self-consistently.This approach,which explicitly accounts for charge relaxation,allows us to treat neutral and(multi-)charged clusters not only at equilibrium but also in dissociative regions.The equilibrium properties,geometries,harmonic spectra,and relative stabilities of the stable isomers of neutral and singly charged clusters in the range n = 1-14,for C_(20)and C_(60),are found to reproduce the results of ab initio calculations.The model is also shown to be successful in describing the stability and fragmentation energies of dictations in the range n = 2-10 and allows the determination of their Coulomb barriers,as examplified for the smallest sizes(C_2~(2+),C_3~(2+),C_4~(2+)).We also present time-dependent mean-field and linear response optical spectra for the C_8 and C_(60)clusters and discuss their relevance with respect to existing calculations.