An analysis of the structural properties of three-dimensional Coulomb clusters confined in a spherical parabolic trap is presented. Based on extensive high-accuracy computer simulations the shell configurations and energies for particle numbers in the range 60 < or = N < or = 160 are reported. Further, the intrashell symmetry and the lowest metastable configurations are analyzed for small clusters and a different type of excited state that does not involve a change of shell configuration is identified.

No abstract

No abstract

An analysis of strong-coupling effects in carrier-carrier scattering in electron-hole plasmas in semiconductors is presented. The conventional approach to scattering and dephasing rates is based on the Born approximation ͑a scattering cross section proportional to the square of the dynamically screened interaction potential͒, and is strictly valid only in the limit of the weakly coupled quantum plasma. Otherwise, strong correlations are expected to become important in the scattering quantities. Therefore, we perform a thorough analysis of scattering rates in the framework of the statically screened T-matrix ͑ladder͒ approximation. We solve the two-particle Schrödinger equation and provide explicit results for the carrier-carrier scattering rates in equilibrium as well as for optical excitation conditions. Numerical results for GaAs show evidence of significant deviations from the common Born approximation. Finally, dynamic screening effects are included approximately. ͓S0163-1829͑99͒01815-9͔