Many-body effects on one-electron energies and wave functions in low-dimensional systems

We have studied the quasiparticle (QP) wave functions and energies of the GaAs(1 1 0) surface and of the cluster Na4 within Hedinʹs GW approximation. We found that the commonly accepted assumption that the Density Functional Theory (DFT)–Local Density Approximation (LDA) wave functions are a very good approximation for the true QP ones can be wrong. We analyze the effect of the resulting changes in the wave functions on the optical spectra.