Ab initiodynamical response of metal monolayers

A. Bergara, V. M. Silkin, E. V. Chulkov, P. M. Echenique
2003 Physical Review B (Condensed Matter)  
Ab initio calculation of the density response function within the random-phase approximation is presented for lithium, berillium, and boron freestanding metal monolayers ͑ML's͒. Although the monolayers manifest common features related to their reduced dimensionality, their different band structures lead to significant modifications in the density response function. Besides the common intraband and interband collective excitations, the beryllium ML also presents characteristic features of
more » ... features of acoustic plasmons associated with the presence of two types of carriers at the Fermi level. Contrary to the bulk, long-wavelength intraband plasmons in lithium and beryllium ML's cannot decay via umklapp processes associated with the band structure. At the same time, these processes lead to a significant reduction of the momentum threshold for decay of these plasmons comparing with a free-electron two-dimensional gas model. It is also shown how a change of the symmetry of the boron ML modifies completely the character of the intraband plasmons.
doi:10.1103/physrevb.67.245402 fatcat:oklqmutbrnemjiqlokbyc2y3kq