A5023697314- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Molecular Junctions and Nanostructures
- Crystallography and molecular interactions
- Magnetism in coordination complexes
- Porphyrin and Phthalocyanine Chemistry
- Advanced Chemical Physics Studies
- Silicon and Solar Cell Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor materials and interfaces
- Organic and Molecular Conductors Research
- Metal complexes synthesis and properties
- Organic Electronics and Photovoltaics
- Thin-Film Transistor Technologies
- Spectroscopy and Quantum Chemical Studies
- Lanthanide and Transition Metal Complexes
- Semiconductor materials and devices
- Electrochemical Analysis and Applications
- Catalysis and Oxidation Reactions
- Laser-induced spectroscopy and plasma
- Chemical Thermodynamics and Molecular Structure
- Quantum and electron transport phenomena
- Metal-Organic Frameworks: Synthesis and Applications
- Photochemistry and Electron Transfer Studies
- Semiconductor Quantum Structures and Devices
TU Bergakademie Freiberg
2010-2020
Institute of Theoretical Physics
2014-2019
Johns Hopkins University
2017
Leibniz Institute for Solid State and Materials Research
2012
National Institute of Standards and Technology
1989-1990
A series of di- and triferrocenyl (hetero)aromatics including 2,5-diferrocenylpyridine (4), 2,6-diferrocenylpyridine (5), 1,3,5-triferrocenylbenzene (9), 2,4,6-triferrocenylpyridine (10), 2,4,6-triferrocenyl-1,3,5-triazine (11) have been prepared using the Negishi C,C cross-coupling protocol. Characterization molecules was performed by spectroscopic means single-crystal X-ray diffraction study (10). The electrochemical properties these compounds were determined cyclic voltammetry, square...
Single crystals of the charge-transfer salt picene/2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane have been grown using physical vapor transport. The crystal structure was determined single-crystal X-ray diffraction. It found that grow in a 1:1 molecular ratio and adopt monoclinic with alternate stacking. Both data Raman measurements show are good quality. From infrared data, charge transfer between acceptor donor molecules estimated to be approximately 0.14–0.19 electron. Transport...
In the Fermi-Löwdin orbital method for implementing self-interaction corrections (FLO-SIC) in density functional theory (DFT), local orbitals used to make are generated a unitary-invariant scheme via choice of Fermi descriptors (FODs). These M positions 3-d space (for an M-electron system) that can be loosely thought as classical electron positions. The minimize DFT energy including SIC obtained by finding optimal FODs. this paper, we present optimized FODs atoms from Li-Kr using unbiased...
The Fermi‐Löwdin orbital self‐interaction correction (FLO‐SIC) methodology is applied to atoms and molecules from the standard G2‐1 test set. For first time FLO‐SIC results for GGA‐type PBE functional are presented. In addition, examples where like any proper SIC provides qualitative improvements compared DFT functionals discussed in detail: dissociation limit , step‐wise linearity behavior fractional occupation, as well significant reduction of error static polarizabilities. Further,...
The correction of the self-interaction error that is inherent to all standard density functional theory calculations an object increasing interest. In this article, we apply very recently developed Fermi-orbital based approach for [M. R. Pederson et al., J. Chem. Phys. 140, 121103 (2014) and M. Pederson, 142, 064112 (2015)] a set different molecular systems. Our study covers systems ranging from simple diatomic large organic molecules. We focus our analysis on direct estimation ionization...
Semi-local approximations to the density functional for exchange-correlation energy of a many-electron system necessarily fail lobed one-electron densities, including not only familiar stretched densities but also less closely-related noded ones. The Perdew-Zunger (PZ) self-interaction correction (SIC) semi-local approximation makes that exact all ground- or excited-state and accurate bonds. When minimization PZ total is made over real localized orbitals, orbital can be noded, leading errors...
Fourteen new derivatives of 9,10-anthraquinone or 9,10-dimethoxyanthracene were designed, synthesised and characterised. Regarding the structure, compounds are π-conjugated (cross linear, respectively) feature thiophene terminated side arms attached to five different positions anthraquinone anthracene core. The synthesis involves a cross-coupling procedure in key reaction steps. Crystal structures 5 19 have been studied. containing title 1–5 can be reduced oxidised by two step redox process....
Using photoelectron spectroscopy we demonstrate charge transfer at an interface between two well-known transition metal phthalocyanines, MnPc and ${\mathrm{F}}_{16}\mathrm{CoPc}$, resulting in charged ${\mathrm{MnPc}}^{\ensuremath{\delta}+}$ ${\mathrm{F}}_{16}{\mathrm{CoPc}}^{\ensuremath{\delta}\ensuremath{-}}$ species. Moreover, the transferred is substantially confined to centers. Density functional theory calculations reveal that a hybrid state formed types of which causes this transfer....
The optical constants together with the magneto-optical Voigt of several phthalocyanine (Pc) and methoxy functionalized tetraphenylporphyrin (TMPP) thin films prepared on silicon substrates are presented. materials investigated MePc Me = Fe, Co, Ni, Cu, Zn MeTMPP Ni. We also compared our results to metal-free H2Pc, H2TPP H2TMPP. experimental will be supported by electronic structure calculations based density functional theory (DFT) interpreted using perimeter model initially proposed Platt....
We present an interpretation of Fermi‐orbital descriptors (FODs) and argue that these carry chemical bonding information. show a bond order derived from FODs agrees well with reference values, highlight optimized FOD positions used within the Fermi‐Löwdin orbital self‐interaction correction (FLO‐SIC) method correspond to expectations Linnett's double‐quartet theory, which is extension Lewis theory. This observation independent underlying exchange‐correlation functional, shown using local...
Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films different create heterostructures which combine electrical capabilities each material. This opens precisely engineer and tune new properties. In particular, similar transition metal phthalocyanines demonstrate hybridization charge transfer properties could lead interesting physical phenomena. Although, when considering dimensions, better...
Relative transition probabilities of 29 lines belonging to the 3s-3p, 3s-4p, 3p-3s'', and 2s2${p}^{4}$-2${s}^{2}$2${p}^{2}$4p arrays N i have been measured in emission with a wall-stabilized arc were normalized an absolute scale utilizing two recent lifetime results. Our experiment was undertaken help resolve some long-standing discrepancies nitrogen data. results are usually slightly larger than earlier measurements but closer agreement calculations. The total uncertainties our individual...
Contact less measurements of the minority carrier “lifetime” and photoconductivity are widely used to characterize material quality investigate defects in a sample. In order interpret these correctly guarantee comparability between different methods, numerical simulation tools were developed. These simulations allow account even for very complex defect models, thus, e.g., enabling trapping effects. Contrary Shockley–Read–Hall model or tool PC1D nearly no assumptions made. Furthermore,...
The effects of electronic states and air exposure on the spectroscopic properties manganese phthalocyanine (MnPc) have been examined. observed features Q-band in absorption spectra can be explained by intrinsic MnPc, i.e., formation singly charged molecules charge transfer excitations. However, reaction MnPc with atmospheric molecular oxygen leads to deviations peak intensities but does not change fundamental characteristics spectra. Nevertheless, changes spin state from S = 3/2 1/2. X-ray...
Without self-interaction corrections or the use of hybrid functionals, approximations to density-functional theory (DFT) often favor intermediate spin systems over high-spin systems. In this paper, we apply recently proposed Fermi–Löwdin-orbital corrected density functional formalism a simple tetra-coordinated Fe(II)-porphyrin molecule and show that energetic orderings S = 1 2 states are changed qualitatively relative results Generalized Gradient Approximation (developed by Perdew, Burke,...
The synthesis of the novel macrocyclic octadentate amino-thiophenolate ligand H(2)L2 (3,7,11,19,23,27-hexaaza-33,34-dithiol-15,31-di(tert-butyl)-tricyclo[27,3,1(13.17)]-tetratriaconta-1(32),13,15,17(34),29,30-hexane) and its ability to support binuclear nickel(II) complexes with dithiolato-bridged square-pyramidal Ni(II) ions are reported. is obtained as hexahydrobromide salt from a Schiff-base condensation reaction between 1,2-bis(4-tert-butyl-2,6-diformylphenylthio)ethane...
We have prepared mixed phthalocyanine films out of MnPc and F16CoPc, which were characterized by means photoemission spectroscopy electron energy-loss spectroscopy. Our data reveal the formation MnPc/F16CoPc charge transfer dimers in analogy to related heterojunction. The electronic excitation spectrum these blends is a new low energy at 0.6 eV. Density functional theory calculations show that signal caused strong absorption between states interface induced two level system.
We derived, implemented, and thoroughly tested the complete analytic expression for atomic forces, consisting of Hellmann-Feynman term Pulay correction, Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method. Analytic forces are shown to be numerically accurate through an extensive comparison obtained from finite differences. Using equilibrium structures a small set molecules were obtained. This work opens possibility routine free geometrical relaxations using FLO-SIC © 2018 Wiley...
The origin of larger<italic>J</italic>values trinuclear bis(oxamidato)<italic>versus</italic>bis(oxamato) type complexes is explained by an interplay with the spin densities their mononuclear precursors.
Four new azulene derivatives featuring two π‐conjugated and sulfur terminated rigid side arms in the 1,3‐positions of core were designed, synthesized, characterized. The syntheses carried out on basis a palladium cross‐coupling procedure key reaction step. crystal structures target compound 3 intermediate compounds 7 9 have been studied. Supporting density functional theory calculations reveal insights into electronic properties particular azulenes. comparison measured UV–Vis, infrared,...
Treatment of the diethyl ester o-phenylenebis(oxamic acid) (opbaH(2)Et(2), 1) with 5/6 equivalent MeNH(2) in abs. EtOH results exclusive formation ethyl o-phenylene(N′-methyl oxamide)(oxamic (opooH(3)EtMe, 2) ca. 50% yield. 2 four equivalents [Me(4)N]OH followed by addition Cu(ClO(4))(2)·6H(2)O gave [Me(4)N](2)[Cu(opooMe)]·H(2)O (3A) 80% As 3A appears to be a hygroscopic solid, related [(n)Bu(4)N](+) salts [(n)Bu(4)N](2)[M(opooMe)]·H(2)O (M = Cu (3B), Ni (4)) have been synthesized. By two...
We present electronic properties of a charge transfer material consisting Manganese(ii)Phthalocyanine (MnPc) and 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), investigated by means photoemission spectroscopy electron energy-loss spectroscopy, as well supporting density functional theory calculations. report the successful formation bulk characterized strong interaction molecular compounds which affects optical significantly. Our investigations reveal significant transfer,...