M. Strange, K. S. Thygesen
We discuss the physical and mathematical meaning of the quasiparticle (QP) wave functions, also known as the Dyson orbitals, in inhomogeneous interacting electron systems. For the specific case of a molecular wire in contact with a metal surface we show, using a simple lattice model and the GW approximation to the electron self-energy, that non-local polarization effects pull the frontier molecular orbitals towards the metal surface while higher/lower lying orbitals are pushed away. This renormalization of the QP wave functions, which is not captured by any semilocal or hybrid exchange-correlation potential, influences both the position and width of the molecular resonances. Inclusion of off-diagonal elements and, to some extent self-consistency, in the GW self-energy is essential to describe the effect.
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http://arxiv.org/abs/1204.5401
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