arXiv subjects
Publications and source records attributed to Caio Lewenkopf.
A new method to obtain a local parameterization for the exchange term in the many--body electronic problem is presented. The approach amounts to the introduction of a coordinate dependent electron effective mass. Numerical results for metallic clusters in the jellium model are compared with other standard methods.
We present an analysis of the temperature dependence of the optical response of small sodium clusters in a temperature range bracketing the melting phase transition. When the temperature increases, the mean excitation energy undergoes a red shift and the plasmon is significantly broadened, in agreement with recent experimental data. We show that the single--particle levels acquire a prominent width and the HOMO--LUMO gap as well as the width of the occupied band are reduced due to large thermal cluster size and shape fluctuations. This results in a sharp increase of the static polarizability with temperature.