TY - JOUR A1 - Xiong, Tao A1 - Włodarczyk, Radosław Stanisław A1 - Gallandi, Lukas A1 - Körzdörfer, Thomas A1 - Saalfrank, Peter T1 - Vibrationally resolved photoelectron spectra of lower diamondoids BT - a time-dependent approach JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry N2 - Vibrationally resolved lowest-energy bands of the photoelectron spectra (PES) of adamantane, diamantane, and urotropine were simulated by a time-dependent correlation function approach within the harmonic approximation. Geometries and normal modes for neutral and cationic molecules were obtained from B3LYP hybrid density functional theory (DFT). It is shown that the simulated spectra reproduce the experimentally observed vibrational finestructure (or its absence) quite well. Origins of the finestructure are discussed and related to recurrences of autocorrelation functions and dominant vibrations. Remaining quantitative and qualitative errors of the DFT-derived PES spectra refer to (i) an overall redshift by ∼0.5 eV and (ii) the absence of satellites in the high-energy region of the spectra. The former error is shown to be due to the neglect of many-body corrections to ordinary Kohn-Sham methods, while the latter has been argued to be due to electron-nuclear couplings beyond the Born-Oppenheimer approximation [Gali et al., Nat. Commun. 7, 11327 (2016)]. Y1 - 2018 U6 - https://doi.org/10.1063/1.5012131 SN - 0021-9606 SN - 1089-7690 VL - 148 IS - 4 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Thierbach, Adrian A1 - Neiss, Christian A1 - Gallandi, Lukas A1 - Marom, Noa A1 - Koerzdoerfer, Thomas A1 - Goerling, Andreas T1 - Accurate Valence Ionization Energies from Kohn-Sham Eigenvalues with the Help of Potential Adjustors JF - Journal of chemical theory and computation N2 - An accurate yet computationally very efficient and formally well justified approach to calculate molecular ionization potentials is presented and tested. The first as well as higher ionization potentials are obtained as the negatives of the Kohn-Sham eigenvalues of the neutral molecule after adjusting the eigenvalues by a recently [Gorling Phys. Rev. B 2015, 91, 245120] introduced potential adjustor for exchange-correlation potentials. Technically the method is very simple. Besides a Kohn-Sham calculation of the neutral molecule, only a second Kohn-Sham calculation of the cation is required. The eigenvalue spectrum of the neutral molecule is shifted such that the negative of the eigenvalue of the highest occupied molecular orbital equals the energy difference of the total electronic energies of the cation minus the neutral molecule. For the first ionization potential this simply amounts to a Delta SCF calculation. Then, the higher ionization potentials are obtained as the negatives of the correspondingly shifted Kohn-Sham eigenvalues. Importantly, this shift of the Kohn-Sham eigenvalue spectrum is not just ad hoc. In fact, it is formally necessary for the physically correct energetic adjustment of the eigenvalue spectrum as it results from ensemble density-functional theory. An analogous approach for electron affinities is equally well obtained and justified. To illustrate the practical benefits of the approach, we calculate the valence ionization energies of test sets of small- and medium-sized molecules and photoelectron spectra of medium-sized electron acceptor molecules using a typical semilocal (PBE) and two typical global hybrid functionals (B3LYP and PBE0). The potential adjusted B3LYP and PBE0 eigenvalues yield valence ionization potentials that are in very good agreement with experimental values, reaching an accuracy that is as good as the best G(0)W(0) methods, however, at much lower computational costs. The potential adjusted PBE eigenvalues result in somewhat less accurate ionization energies, which, however, are almost as accurate as those obtained from the most commonly used G(0)W(0) variants. Y1 - 2017 U6 - https://doi.org/10.1021/acs.jctc.7b00490 SN - 1549-9618 SN - 1549-9626 VL - 13 SP - 4726 EP - 4740 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Knight, Joseph W. A1 - Wang, Xiaopeng A1 - Gallandi, Lukas A1 - Dolgounitcheva, Olga A1 - Ren, Xinguo A1 - Ortiz, J. Vincent A1 - Rinke, Patrick A1 - Körzdörfer, Thomas A1 - Marom, Noa T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules III: A Benchmark of GW Methods JF - Journal of chemical theory and computation N2 - The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, and perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green’s function (scGW0), non-self-consistent G0W0 based on several mean-field starting points, and a “beyond GW” second-order screened exchange (SOSEX) correction to G0W0. We also describe the implementation of the self-consistent Coulomb hole with screened exchange method (COHSEX), which serves as one of the mean-field starting points. The best performers overall are G0W0+SOSEX and G0W0 based on an IP-tuned long-range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00871 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 615 EP - 626 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Gallandi, Lukas A1 - Marom, Noa A1 - Rinke, Patrick A1 - Körzdörfer, Thomas T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules II: Non-Empirically Tuned Long-Range Corrected Hybrid Functionals JF - Journal of chemical theory and computation N2 - The performance of non-empirically tuned long-range corrected hybrid functionals for the prediction of vertical ionization potentials (IPs) and electron affinities (EAs) is assessed for a set of 24 organic acceptor molecules. Basis set extrapolated coupled cluster singles, doubles, and perturbative triples [CCSD(T)] calculations serve as a reference for this study. Compared to standard exchange-correlation functionals, tuned long-range corrected hybrid functionals produce highly reliable results for vertical IPs and EAs, yielding mean absolute errors on par with computationally more demanding GW calculations. In particular, it is demonstrated that long-range corrected hybrid functionals serve as ideal starting points for non-self-consistent GW calculations. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00873 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 605 EP - 614 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Gallandi, Lukas A1 - Körzdörfer, Thomas T1 - Long-Range Corrected DFT Meets GW: Vibrationally Resolved Photoelectron Spectra from First Principles JF - Journal of chemical theory and computation N2 - We propose an entirely nonempirical and computationally efficient scheme to calculate highly reliable vibrationally resolved photoelectron spectra for molecules from first principles. To this end, we combine nonempirically tuned long-range corrected hybrid functionals with non-self-consistent many-body perturbation theory in the G(0)W(0) approximation and a Franck-Condon multimode analysis based on DFT-calculated frequencies. The vibrational analysis allows for a direct comparison of the GW-calculated spectra to gas-phase ultraviolet photoelectron measurements of neutral and anionic molecules, respectively. Direct comparison of the calculated peak maxima with experiment yields mean absolute errors below 0.1 eV for ionization potentials, electron affinities, and fundamental gaps, clearly outperforming commonly used G(0)W(0) approaches at similar numerical costs. Y1 - 2015 U6 - https://doi.org/10.1021/acs.jctc.5b00820 SN - 1549-9618 SN - 1549-9626 VL - 11 IS - 11 SP - 5391 EP - 5400 PB - American Chemical Society CY - Washington ER -