a CNRS-CEA, Laboratoire des Solides Irradiés, Ecole Polytechnique, 91128, Palaiseau, France
b Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica, Università di Roma “Tor Vergata” I-00133, Roma, Italy
Abstract:
We discuss a method for first-principles calculations of photoemission spectra in small clusters, going well beyond a standard density functional theory-local density approximation (DFT-LDA) approach. Starting with a DFT-LDA calculation, we evaluate self-energy contributions to the quasiparticle energies of an electron or hole in the GW scheme, where the self-energy Σ = GW is constructed from the one-particle Green's function G and the RPA screened Coulomb interaction W. The contributions of structural relaxation are taken into account. We show the importance of these effects at the example of the photoemission spectrum of SiH4. We also briefly discuss results for longer hydrogenated silicon chains, and address the problem of optical absorption.