Accurate absolute core-electron binding energies of molecules, solids, and surfaces from first-principles calculations

Abstract

Core-electron x-ray photoelectron spectroscopy is a powerful technique for studying the electronic structure and chemical composition of molecules, solids and surfaces. However, the interpretation of measured spectra and the assignment of peaks to atoms in specific chemical environments is often challenging. Here, we address this problem and introduce a parameter-free computational approach for calculating absolute core-electron binding energies. In particular, we demonstrate that accurate absolute binding energies can be obtained from the total energy difference of the ground state and a state with an explicit core hole when exchange and correlation effects are described by a recently developed meta-generalized gradient approximation and relativistic effects are included even for light elements. We carry out calculations for molecules, solids and surface species and find excellent agreement with available experimental measurements. For example, we find a mean absolute error of only 0.16 eV for a reference set of 103 molecular core-electron binding energies. The capability to calculate accurate absolute core-electron binding energies will enable new insights into a wide range of chemical surface processes that are studied by x-ray photoelectron spectroscopy. arXiv:1904.04823v1 [cond-mat.mtrl-sci]

A combined density functional theory and x-ray photoelectron spectroscopy study of the aromatic amino acids

“…Comparing the Koopmans' and ΔSCF results for 3-methyl-1H-indole ( 23) and 3-ethyl-1H-indole (24) a considerable change in BE for C α and C β is observed as in the previous cases discussed. A systematic difference in the ΔSCF BEs of C 2 and C 7a is noted across all molecules in the series except (21), even if the six-membered ring is removed as is the case in 2-amino-3-(5-methyl-1H-pyrrol-3-yl)propanoic acid ( 25) and 2-amino-3-(1H-pyrrol-2-yl)propanoic acid (26).…”

“…Furthermore, in Trp the BE of C β is surprisingly close to that of both C 2 and C 7a in the gas phase and the same as C 7a in the solid state, which cannot be explained by arguments based purely on electronegativity. On the contrary, since they each neighbour an N atom, one would expect the BE of C α to be close to that of C 2 and C 7a , which is not the case in either Trp, (25), or (26). In addition to next-nearest neighbour effects, this can also be explained by the protonation state of the N atoms.…”

All-Electron Gaussian-Based G0W0 for Valence and Core Excitation Energies of Periodic Systems

“…One state-of-the-art method for calculating CEBEs is the Δself-consistent-field (ΔSCF) approach based on KS-DFT [94], which has been shown to predict accurate CEBEs with approximately 0.2-0.3 eV errors for small molecules [95,96]. Recently, a restricted open-shell Kohn-Sham (ROKS) ap-TABLE V. Core excitation binding energies (defined in Eq.…”

Accurate Absolute and Relative Core-Level Binding Energies from GW

“…This deviation is quite sensitive to the XC functional. 15 The best results for absolute core excitations have been obtained using the TPSS 16 and SCAN 17 meta-generalized gradient approximations. The reported mean absolute deviations from the experiment lie in the range of ∼0.2 eV for benchmark sets of small molecules.…”

“…The ΔSCF calculations are performed with the PBE0 60 , 61 functional and are carefully converged by adding additional tight basis functions to standard Gaussian basis sets for the core-hole calculation. 66 Following a recently proposed ΔSCF simulation protocol, 17 we include scalar relativistic effects self-consistently via the zeroth-order regular approximation (ZORA). 67 Our BEs obtained from ΔSCF-PBE0, with an overall MAE of 0.3 eV, agree much better with experiment than those reported in previous studies (0.7 eV), 15 which must be attributed to incomplete basis sets and the neglect of relativistic effects.…”