Quasiparticles in van der Waals bonded hexagonal Boron Nitride structures

Kimika Teorikoa Seminar

We compute and track the impact of truly nonlocal-correlation effects on the quasi-particle (QP) band-structure of hexagonal boron-nitride (h-BN) systems. To that end, we start with the consistent-exchange vdW-DF-cx version of the van der Waals density functional (vdW-DF) method for exchange-correlation (XC) functional design and enforce piece-wise linearity in the energy changes with partial charging, using the Koopmans-integer (KI) DFT framework.

Our approach and results (denoted KI-CX) extends present-standard use of KI DFT to capture, for example, the impact of the interlayer coupling on the QPs. We contrast KI-CX and KI-PBE results for the QP band-structure and compare with both GW calculations and experimental observations of the QP gaps. We find that KI-CX brings improvements in the h-BN QP energy description and generally agrees with GW studies.