Efficient treatment of many-body effects in weakly bound hybrid interfaces

Hybrid inorganic/organic systems (HIOS) are receiving increasing attention due to interesting physical processes at the interface, such as charge transfer, charge redistribution, and energy-conversion mechanisms. In general, electronic and optical properties of HIOS can be computed accurately by means of many-body perturbation theory in the framework of the GW approach and the Bethe-Salpeter equation (BSE). However, these calculations represent a significant challenge due to their large system sizes. In this work, we start from an additive ansatz for the polarizability [1], which is justified for weakly bound systems, i.e., interfaces dominated by van der Waals and dipole interactions. In this method, the individual contributions of the constituents in their respective unit cells are expanded into the basis of the corresponding supercell and summed up to either enter the GW self-energy or the BSE. A corresponding approach is presented for the electron-phonon self-energy. Both methods are implemented in the all electron full-potential package exciting [2] that is based on the linearized augmented plane-wave plus local-orbital framework. We apply the developed methodology to compute the level alignment at selected HIOS, accounting for renormalization effects due to electron-electron and electron-phonon interactions, as well as optical spectra considering excitonic effects.

[1]F. Xuan, et al., J. Chem. Theory. Comput. 15, 3824 (2019).

[2]A. Gulans, et al., J. Phys. Condens. Matter. 26, 363202 (2014).