Surface screening and lifetime of image states on Li(110)

We here present the calculation results of the lifetime tau = (h) over bar/ Gamma of the n = 1, 2 image states on the Li(110) surface. The linewidth Ga mma of an image state is evaluated as the imaginary part of the electron se lf-energy Sigma projected over the state itself. The GW approximation is ut ilized for the calculation of Sigma. Different approximations are used to c larify the role of the surface screening on the lifetime of image states. T he n = 1 image state lifetime is found to be of 18 fs, which is very close to both theoretical and experimental predictions of the lifetime of the fir st image state on Cu(111). (C) 1999 Elsevier Science B.V. All rights reserv ed.