  We predict the strong enhancement in the photoabsorption of small Mg clusters
in the region of 4-5 eV due to the resonant excitation of the plasmon
oscillations of cluster electrons. The photoabsorption spectra for neutral Mg
clusters consisting of up to N=11 atoms have been calculated using ab initio
framework based on the time dependent density functional theory (TDDFT). The
nature of predicted resonances has been elucidated by comparison of the results
of the ab initio calculations with the results of the classical Mie theory. The
splitting of the plasmon resonances caused by the cluster deformation is
analysed. The reliability of the used calculation scheme has been proved by
performing the test calculation for a number of sodium clusters and the
comparison of the results obtained with the results of other methods and
experiment.
