Density functional theory simulations of B K and N K NEXAFS spectra of h-BN/transition metal(111) interfaces

The electronic structure and the corresponding B K and N K near-edge x-ray fine structure (NEXAFS) spectra of epitaxially grown h-BN on Ni(111), Pt(111), and Rh(111) surfaces are investigated by density functional theory. The calculations are carried out using the WIEN2k program package applying the augmented-plane-wave + local orbitals (APW + lo) method. The NEXAFS spectra are simulated using a 3 x 3 x 1 super cell and considering the final state rule by means of a (partial) core hole for the corresponding atom. The influence of a full or partial core hole is shown for the h-BN/Ni(111) system, for which the best agreement with the experimental spectra is found when half a core hole is assumed. All characteristic features of the experimental spectra are well reproduced by theory, including the angular dependences. The bonding effects are investigated by comparing the spectra of bulk h-BN with those of the h-BN/Ni(111) system. An analysis of both the density of states and charge densities reveals strong N-p(z)-Ni-d(z)(2) bonding/antibonding interactions. In the case of Pt(111) and Rh(111) surfaces, we discuss the effects of the nanomesh structures in terms of simple 1 x 1 commensurate models.