Calculation of the graphene C1score level binding energy

Abstract

X-ray photoelectron spectroscopy (XPS) combined with first principles modeling is a powerful tool for determining the chemical composition and electronic structure of novel materials. Of these, graphene is an especially important model system for understanding the properties of other carbon nanomaterials. Here, we calculate the carbon 1s core level binding energy of pristine graphene using two methods based on density functional theory total energy differences: a calculation with an explicit core-hole (∆KS), and a novel all-electron extension of the delta self-consistent field (∆SCF) method. We study systematically their convergence and computational workload, and the dependence of the energies on the chosen exchange-correlation functional. The ∆SCF method is computationally more expensive, but gives consistently higher C 1s binding energies. Although there is a significant functional dependence, the binding energy calculated using the PBE functional is found to be remarkably close to what has been measured for graphite.

Spectroscopic observation of oxygen dissociation on nitrogen-doped graphene

“…However, it is not clear whether all other binding energies are similarly affected, or is the bulk value more sensitive since it is more influenced by the long-range metallic screening that is perturbed by the moiré. The other factor is the known underestimation of the values 42 , which yield a pristine graphene C 1 s at 283.827 eV for our simulation parameters, about 0.6 eV (0.02%) lower than the experimental graphite value. For ease of comparison to the experimental data, we have aligned the calculated BEs to the relevant experimental references (pristine graphene C 1 s at 284.16 eV, graphitic N 1 s at 400.9 eV, pristine graphene epoxide O 1 s at 531.2 eV) in Table 2 , with the structures referenced to the panels of Fig.…”

“…For atomistic simulations, we used density functional theory modelling implemented in the GPAW simulation package 53 . For each of the studied structures, we used a 6 × 6 supercell of graphene with 10 Å of vacuum, the Perdew-Burke-Erzerhof (PBE) functional, and a Monkhorst-Pack k -point mesh of 5 × 5 × 1 (these parameters are sufficient for core level binding energies converged to within 100 meV) 42 . After introducing a N site, we relaxed the structure until maximum forces were <0.02 eV/Å.…”

Ultrafast electron injection into photo-excited organic molecules

“…To compare computational results with the experiment, we focus on the LUMO* case, with an added valence electron as eventually attracted from the substrate to screen the perturbation. [23][24][25][26][27] This corresponds to a fully relaxed electronic configuration after the molecule is ionized. The attractive potential introduced by the core hole lowers the energy of the molecular orbitals with respect to the ground state.…”

Ab initiodensity functional theory study on the atomic and electronic structure of GaP/Si(001) heterointerfaces

“…The Ga 2p 3/2 , P 2p 3/2 , and Si 2p 3/2 core-level binding energies of atoms at interfaces and in the "bulk" (in GaP and Si layers above and below the interface) were computed for three interface models. The delta Kohn-Sham ( KS) method [39,40] within the grid-based projector-augmented wave (PAW) code GPAW [41] was used, which enables highly parallel and efficient core-level calculations. In this method, the core-level binding energy is the total energy difference between the ground state and the first core-ionized state, explicitly introduced for each element via a PAW data set with its 2p 3/2 occupancy reduced by one electron.…”