Influence of impurity on isotope coefficient of superconductors

We study the influence of anisotropy of the impurity potential on isotope coefficient of an impure superconductor in the Born limit. From the isotope coefficient of non-magnetic and magnetic impurities including an angle-resolved Fermi surface density of state, anisotropy order parameter and impure potential, we make the assumption that the form of them are in the harmonic form and are investigated. Our numerical calculation of isotope coefficient can fit well with experimental data of high-Tc superconductors.