We present a new theoretical approach for the simulations of X-ray photoelectron spectra of strongly correlated molecular systems that combines multireference algebraic diagrammatic construction theory (MR-ADC) [J. Chem. Phys., 2018,...

Ultrafast charge delocalization dynamics in excited states of internal donor–acceptor copolymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) was studied by resonant Auger spectroscopy (RAS) measured around silicon and sulfur K edges using the core-hole clock approach. The effect of the thermal annealing treatment at 100 and 200 °C on the charge transfer delocalization times and molecular orientation were probed. Exponential dependence of charge transfer times (τ CT) with photon energy was found at both absorption edges with a decreasing curve slope with the thermal treatment. Features characteristics of the Auger Resonant Raman effect were observed at sulfur KL2,3L2,3 Auger decay spectra. Edge-on and plane-on molecular orientations with respect to the substrate surface were measured for the thiophene and benzothiadiazole units, respectively, using angular-dependent NEXAFS spectra at the S K edge. Molecular orientation of silafluorene was also probed by NEXAFS at the Si K edge. The improvement of the polymer ordering with annealing was evaluated by NEXAFS. Differences in charge transfer times at Si and S K edges may be related to the localized–delocalized character of the molecular orbitals (MOs) involved in those excitation processes, which was corroborated by theoretical calculations at the Hartree–Fock (HF) level, with explicit relaxation of molecular orbitals due to the core-hole. The molecular orientation effect in the charge transfer process was also investigated through the nonadiabatic coupling matrix elements involving the first low-lying excited states in both K edge excitations.

Correction for ‘Simulating X-ray photoelectron spectra with strong electron correlation using multireference algebraic diagrammatic construction theory’ by Carlos E. V. de Moura and Alexander Yu. Sokolov, Phys. Chem. Chem. Phys., 2022, 24, 4769–4784, DOI: 10.1039/D1CP05476G.

Potential energy curves and inner-shell ionization energies of carbon monoxide, oxygen and nitrogen molecules were calculated using several forms of the inner-shell multiconfigurational self-consistent field (IS-MCSCF) method-a recently proposed protocol to obtain specifically converged inner-shell states at this level. The particular forms of the IS-MCSCF method designated IS-GVB-PP, IS-FVBL and IS-CASSCF stand for perfect pairing generalized valence bond, full valence bond-like MCSCF and complete active space self consistent field, respectively. A comparison of these different versions of the IS-MCSCF method was carried out for the first time. The results indicate that inner-shell states are described accurately even for the simplest version of the method (IS-GVB-PP). Dynamic correlation was recovered by multireference configuration interaction or multireference perturbation theory. For molecules not having equivalent atoms, all methods led to comparable and accurate transition energies. For molecules with equivalent atoms, the most accurate results were obtained by multireference perturbation theory. Scalar relativistic effects were accounted for using the Douglas-Kroll-Hess Hamiltonian.

Potential energy curves for inner-shell states of nitrogen and carbon dioxide molecules are calculated by inner-shell complete active space self-consistent field (CASSCF) method, which is a protocol, recently proposed, to obtain specifically converged inner-shell states at multiconfigurational level. This is possible since the collapse of the wave function to a low-lying state is avoided by a sequence of constrained optimization in the orbital mixing step. The problem of localization of K-shell states is revisited by calculating their energies at CASSCF level based on both localized and delocalized orbitals. The localized basis presents the best results at this level of calculation. Transition energies are also calculated by perturbation theory, by taking the above mentioned MCSCF function as zeroth order wave function. Values for transition energy are in fairly good agreement with experimental ones. Bond dissociation energies for N(2) are considerably high, which means that these states are strongly bound. Potential curves along ground state normal modes of CO(2) indicate the occurrence of Renner-Teller effect in inner-shell states.