Quasiparticle lifetimes in magnesium clusters modeled by self-consistent GWΓ calculations

Abstract

Quasiparticle (QP) lifetimes in magnesium clusters are calculated using many-body Green's-function theory. We analyze the effect of the self-consistency of the one-particle Green's function G on the calculations and demonstrate the necessity of the implementation of such a self-consistency. Based on hot-electron and hot-hole lifetimes in Mg[subscript 40] calculated by the GWΓ method, we find that in the low-energy excitation regime, the QP lifetimes are longer than those in the free-electron gas with the electron density r[subscript s]=2.66 (3s[superscript 2] of the bulk Mg) due to the lack of states available for transitions. In the high-excitation-energy regime, scaled lifetimes of hot electrons converge to the range of 21–24 fs eV[superscript 2]. Scaled lifetimes of hot holes in this regime are shorter than those of hot electrons and decrease slightly with increasing excitation energies.