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 - Sutton, Christopher A1 - Körzdörfer, Thomas A1 - Gray, Matthew T. A1 - Brunsfeld, Max A1 - Parrish, Robert M. A1 - Sherrill, C. David A1 - Sears, John S. A1 - Bredas, Jean-Luc T1 - Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We investigate the torsion potentials in two prototypical pi-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains. Y1 - 2014 U6 - https://doi.org/10.1063/1.4863218 SN - 0021-9606 SN - 1089-7690 VL - 140 IS - 5 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Sutton, Christopher A1 - Körzdörfer, Thomas A1 - Coropceanu, Veaceslav A1 - Bredas, Jean-Luc T1 - Toward a robust quantum-chemical description of organic mixed-valence systems JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - The electronic coupling between redox sites in mixed-valence systems has attracted the interest of the chemistry community for a long time. Many computational studies have focused on trying to determine its magnitude as a function of the nature of the redox sites and of the bridge(s) between them. However, in most instances, the quantum-chemical methodologies that have been employed suffer from intrinsic errors that lead to either an overlocalized or an overdelocalized character of the electronic structure. These deficiencies prevent an accurate depiction of the degree of charge (de)localization in the system and, as a result, of the extent of electronic coupling. Here we use nonempirically tuned long-range corrected density functional theory and show that it provides a robust, efficient approach to characterize organic mixed-valence systems. We first demonstrate the performance of this approach via a study of representative Robin-Day class-II (localized) and class-III (delocalized) complexes. We then examine a borderline class-II/class-III complex, which had proven difficult to describe accurately with standard density functional theory and Hartree-Fock methods. Y1 - 2014 U6 - https://doi.org/10.1021/jp410461v SN - 1932-7447 VL - 118 IS - 8 SP - 3925 EP - 3934 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Sun, Haitao A1 - Ryno, Sean A1 - Zhong, Cheng A1 - Ravva, Mahesh Kumar A1 - Sun, Zhenrong A1 - Körzdörfer, Thomas A1 - Bredas, Jean-Luc T1 - Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)-Tuned Range-Separated Density Functional Approach JF - Journal of chemical theory and computation N2 - We propose a new methodology for the first principles description of the electronic properties relevant for charge transport in organic molecular crystals. This methodology, which is based on the combination of a nonempirical, optimally tuned range separated hybrid functional with the polarizable continuum model, is applied to a series of eight representative molecular semiconductor crystals. We show that it provides ionization energies, electron affinities, and transport gaps in very good agreement with experimental values, as well as with the results of many-body perturbation theory-within the GW approximation at a fraction of the computational cost. Hence, this approach represents an easily applicable and computationally efficient tool to estimate the gas-to crystal phase shifts of the frontier-orbital quasiparticle energies in organic electronic materials. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.6b00225 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 2906 EP - 2916 PB - American Chemical Society CY - Washington ER - TY - INPR A1 - Megow, Jörg A1 - Körzdörfer, Thomas A1 - Renger, Thomas A1 - Sparenberg, Mino A1 - Blumstengel, Sylke A1 - May, Volkhard T1 - Reply to "Comment on 'Calculating Optical Absorption Spectra of Thin Polycrystalline Organic Films: Structural Disorder and Site-Dependent van der Waals Interaction" T2 - The journal of physical chemistry : C, Nanomaterials and interfaces Y1 - 2015 U6 - https://doi.org/10.1021/acs.jpcc.5b05536 SN - 1932-7447 VL - 119 IS - 32 SP - 18818 EP - 18820 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Megow, Jörg A1 - Körzdörfer, Thomas A1 - Renger, Thomas A1 - Sparenberg, Mino A1 - Blumstengel, Sylke A1 - Henneberger, Fritz A1 - May, Volkhard T1 - Calculating Optical Absorption Spectra of Thin Polycrystalline Organic Films: Structural Disorder and Site-Dependent van der Waals Interaction JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - We propose a new approach for calculating the change of the absorption spectrum of a molecule when moved from the gas phase to a crystalline morphology. The so-called gas-to-crystal shift Delta epsilon(m) is mainly caused by dispersion effects and depends sensitively on the molecules specific position in the nanoscopic setting. Using an extended dipole approximation, we are able to divide Delta epsilon(m)= -QW(m) in two factors, where Q depends only on the molecular species and accounts for all nonresonant electronic transitions contributing to the dispersion while W-m is a geometry factor expressing the site dependence of the shift in a given molecular structure. The ability of our approach to predict absorption spectra is demonstrated using the example of polycrystalline films of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI). Y1 - 2015 U6 - https://doi.org/10.1021/acs.jpcc.5b01587 SN - 1932-7447 VL - 119 IS - 10 SP - 5747 EP - 5751 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Marom, Noa A1 - Körzdörfer, Thomas A1 - Ren, Xinguo A1 - Tkatchenko, Alexandre A1 - Chelikowsky, James R. T1 - Size effects in the interface level alignment of dye-Sensitized TiO2 clusters JF - The journal of physical chemistry letters N2 - The efficiency of dye-sensitized solar cells (DSCs) depends critically on the electronic structure of the interfaces in the active region. We employ recently developed dispersion-inclusive density functional theory (DFT) and GW methods to study the electronic structure of TiO2 clusters sensitized with catechol molecules. We show that the energy level alignment at the dye-TiO2 interface is the result of an intricate interplay of quantum size effects and dynamic screening effects and that it may be manipulated by nanostructuring and functionalizing the TiO2. We demonstrate that the energy difference between the catechol LUMO and the TiO2 LUMO, which is associated with the injection loss in DSCs, may be reduced significantly by reducing the dimensions of nanostructured TiO2 and by functionalizing the TiO2 with wide-gap moieties, which contribute additional screening but do not interact strongly with the frontier orbitals of the TiO2 and the dye. Precise control of the electronic structure may be achieved via "interface engineering" in functional nanostructures. Y1 - 2014 U6 - https://doi.org/10.1021/jz5008356 SN - 1948-7185 VL - 5 IS - 14 SP - 2395 EP - 2401 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Marom, Noa A1 - Caruso, Fabio A1 - Ren, Xinguo A1 - Hofmann, Oliver T. A1 - Körzdörfer, Thomas A1 - Chelikowsky, James R. A1 - Rubio, Angel A1 - Scheffler, Matthias A1 - Rinke, Patrick T1 - Benchmark of GW methods for azabenzenes JF - Physical review : B, Condensed matter and materials physics N2 - Many-body perturbation theory in the GW approximation is a useful method for describing electronic properties associated with charged excitations. A hierarchy of GW methods exists, starting from non-self-consistent G(0)W(0), through partial self-consistency in the eigenvalues and in the Green's function (scGW(0)), to fully self-consistent GW (scGW). Here, we assess the performance of these methods for benzene, pyridine, and the diazines. The quasiparticle spectra are compared to photoemission spectroscopy (PES) experiments with respect to all measured particle removal energies and the ordering of the frontier orbitals. We find that the accuracy of the calculated spectra does not match the expectations based on their level of self-consistency. In particular, for certain starting points G(0)W(0) and scGW(0) provide spectra in better agreement with the PES than scGW. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevB.86.245127 SN - 1098-0121 VL - 86 IS - 24 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Körzdörfer, Thomas A1 - Parrish, Robert M. A1 - Sears, John S. A1 - Sherrill, C. David A1 - Bredas, Jean-Luc T1 - On the relationship between bond-length alternation and many-electron self-interaction error JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - Predicting accurate bond-length alternations (BLAs) in long conjugated molecular chains has been a major challenge for electronic-structure theory for many decades. While Hartree-Fock (HF) overestimates BLA significantly, second-order perturbation theory and commonly used density functional theory (DFT) approaches typically underestimate it. Here, we discuss how this failure is related to the many-electron self-interaction error (MSIE), which is inherent to both HF and DFT approaches. We use tuned long-range corrected hybrids to minimize the MSIE for a series of polyenes. The key result is that the minimization of the MSIE alone does not yield accurate BLAs. On the other hand, if the range-separation parameter is tuned to yield accurate BLAs, we obtain a significant MSIE that grows with chain length. Our findings demonstrate that reducing the MSIE is one but not the only important aspect necessary to obtain accurate BLAs from density functional theory. Y1 - 2012 U6 - https://doi.org/10.1063/1.4752431 SN - 0021-9606 VL - 137 IS - 12 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Körzdörfer, Thomas A1 - Parrish, Robert M. A1 - Marom, Noa A1 - Sears, John S. A1 - Sherrill, C. David A1 - Bredas, Jean-Luc T1 - Assessment of the performance of tuned range-separated hybrid density functionals in predicting accurate quasiparticle spectra JF - Physical review : B, Condensed matter and materials physics N2 - Long-range corrected hybrid functionals that employ a nonempirically tuned range-separation parameter have been demonstrated to yield accurate ionization potentials and fundamental gaps for a wide range of finite systems. Here, we address the question of whether this high level of accuracy is limited to the highest occupied/lowest unoccupied energy levels to which the range-separation parameter is tuned or whether it is retained for the entire valence spectrum. We examine several pi-conjugated molecules and find that orbitals of a different character and symmetry require significantly different range-separation parameters and fractions of exact exchange. This imbalanced treatment of orbitals of a different nature biases the resulting eigenvalue spectra. Thus, the existing schemes for the tuning of range-separated hybrid functionals, while providing for good agreement between the highest occupied energy level and the first ionization potential, do not achieve accuracy comparable to reliable G(0)W(0) computations for the entire quasiparticle spectrum. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevB.86.205110 SN - 1098-0121 VL - 86 IS - 20 PB - American Physical Society CY - College Park ER -