Controlling polarization at insulating surfaces: quasiparticle calculations for molecules adsorbed on insulator films

TL;DR

This paper uses quasiparticle calculations to show how polarization effects at insulator surfaces influence molecular excitation spectra, with implications for tuning electronic properties in surface science and molecular electronics.

Contribution

It demonstrates the controllability of polarization effects on excitation spectra through film thickness variation using G0W0 calculations.

Findings

Polarization effects significantly alter molecular excitation spectra.

Film thickness controls the magnitude of polarization effects.

Surface polarization impacts interpretation of surface science experiments.

Abstract

By means of quasiparticle-energy calculations in the G0W0 approach, we show for the prototypical insulator/semiconductor system NaCl/Ge(001) that polarization effects at the interfaces noticeably affect the excitation spectrum of molecules adsorbed on the surface of the NaCl films. The magnitude of the effect can be controlled by varying the thickness of the film, offering new opportunities for tuning electronic excitations in e.g. molecular electronics or quantum transport. Polarization effects are visible even for the excitation spectrum of the NaCl films themselves, which has important implications for the interpretation of surface science experiments for the characterization of insulator surfaces.