Eur. Phys. J. D 4, 343-352 (1998)
https://doi.org/10.1007/s100530050218

Plasmon response in K, Na and Li clusters: systematics using the separable random-phase-approximation with pseudo-Hamiltonians

¹ Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow region, Russia
² Technische Universität Dresden, Institut für Analysis, 01062 Dresden, Germany
³ Institut für Theoretische Physik, Universität Erlangen, Staudtstrasse 7, 91058 Erlangen, Germany
⁴ Departament de Física Universitat de les Illes Balears, 07071 Palma de Mallorca, Spain

Corresponding author: ^a reinhard@theorie2.physik.uni-erlangen.de

Received: 22 April 1998
Accepted: 24 July 1998
Published online: 15 December 1998

Abstract

The systematics of the plasmon response in spherical K, Na and Li clusters in a wide size region is studied. Two simplifying approximations whose validity has been established previously are considered: (a) a separable approach to the random-phase-approximation, involving an expansion of the residual interaction into a sum of separable terms, (b) the electron-ion interaction is modeled within the pseudo-Hamiltonian jellium model (PHJM) including nonlocal effects by means of realistic atomic pseudoHamiltonians. In cases where nonlocal effects turn out to be negligible, the Structure Averaged Jellium Model (SAJM) has been used. The leading role of Landau damping in forming the plasmon width in medium and large clusters is demonstrated. Good agreement with available experimental data is achieved for K, Na (using the SAJM) and small Li clusters (invoking the PHJM). The trends for peak position and width are generally well reproduced, even up to details of the Landau fragmentation in several clusters. Less good agreement, however, is found for large Li clusters. The possible reasons of the discrepancy are discussed.