Linear response to spin-dependent and spin-independent fields of alkali metal clusters

We have obtained the dipole response functions of alkali-metal clusters to spin-dependent and spin-independent fields within the framework of the time -dependent local-spindensity approximation. As test cases we have studied t he response of spherical jellium clusters with spin-saturated configuration s (Na-9(+), Na-8 and Na-20) and with fully spin-polarized configurations (t he spherical isomer of Na-6(+) and Na-13). For a spin-dependent excitation we have obtained in all these clusters a strongly collective spin mode of s urface type lying at lower energies than the unperturbed particle-hole exci tations. This mode uncouples cleanly from the electric dipole mode (Mie pla smon) in the case of spin-saturated clusters, but if the ground state break s spin symmetry by a finite spin polarization the two modes Nm out to be in tertwined in the responses to spin-dependent as well as spin-independent fi elds.