A5003849497- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-Matter Interactions and Applications
- Magnetism in coordination complexes
- Chemical Reactions and Mechanisms
- Iron oxide chemistry and applications
- Metal complexes synthesis and properties
- Electrocatalysts for Energy Conversion
- Advanced NMR Techniques and Applications
- X-ray Diffraction in Crystallography
- Catalysis and Oxidation Reactions
- Ammonia Synthesis and Nitrogen Reduction
- Radioactive element chemistry and processing
- Electrochemical Analysis and Applications
- Metal-Catalyzed Oxygenation Mechanisms
- CO2 Reduction Techniques and Catalysts
- Molecular spectroscopy and chirality
- Quantum, superfluid, helium dynamics
- Atmospheric chemistry and aerosols
- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Machine Learning in Materials Science
- Molecular Junctions and Nanostructures
Technical University of Munich
2022-2025
University of Rostock
2015-2025
Helmholtz-Zentrum Berlin für Materialien und Energie
2013-2017
University of Kerbala
2017
King Abdulaziz University
2016-2017
Monash University
2017
Rostocker Zentrum zur Erforschung des Demografischen Wandels
2017
University of Kaiserslautern
2013
Lomonosov Moscow State University
2005-2010
Institute for Physics
2010
In this Article we describe the OpenMolcas environment and invite computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during transition from commercial MOLCAS product platform. paper initially describes technical details software development This is followed by brief presentations many methods, implementations, features program suite. These include novel wave function methods such as stochastic complete active...
The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in stable branch package or via interfaces other packages. These span wide range topics computational and presented thematic sections: electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features. This report offers an overview chemical phenomena processes can...
This review provides an overview of the different methods and computer codes that are used to interpret 2p x-ray absorption spectra 3d transition metal ions. We first introduce basic parameters give used. start with semi-empirical multiplet compare available. A special chapter is devoted user friendly interfaces have been written on basis these codes. Next we discuss principle based band structure, including a Density Functional theory approaches. also first-principle from cluster...
We discuss the system-specific optimization of long-range separated density functional theory (DFT) for prediction electronic properties relevant a photocatalytic cycle based on an Ir(III) photosensitizer (IrPS). Special attention is paid to charge-transfer properties, which are key importance photoexcitation dynamics, but and cannot be correctly described by means conventional DFT. The range-separation parameter using $\Delta$SCF method discussed IrPS including its derivatives complexes...
Nonradiative decay channels in the L-edge fluorescence yield spectra from transition-metal-aqueous solutions give rise to spectral distortions with respect x-ray transmission spectra. Their origin is unraveled here using partial and inverse yields on microjet combined multireference ab initio electronic structure calculations. Comparing Fe2+, Fe3+, Co2+ systems we demonstrate quantify unequivocally state-dependent electron delocalization within manifold of d orbitals as one this observation.
Abstract X‐ray spectroscopy is one of the most powerful tools to access structure and properties matter in different states aggregation as it allows trace atomic molecular energy levels course various physical chemical processes. spectroscopic techniques probe local electronic a particular atom its environment, contrast ultraviolet/visible (UV/Vis) spectroscopy, where transitions generally occur between delocalized orbitals. Complementary information provided by using combination absorption,...
Fundamental processes: Charge donation/backdonation in the [Fe(CO)5] molecule solution was measured by resonant inelastic X-ray scattering. This method can be used to selectively probe electronic structure at each atom iron–carbonyl bond. As a service our authors and readers, this journal provides supporting information supplied authors. Such materials are peer reviewed may re-organized for online delivery, but not copy-edited or typeset. Technical support issues arising from (other than...
Resonant inelastic X-ray scattering (RIXS) and absorption (XA) experiments at the iron L- nitrogen K-edge are combined with high-level first-principles restricted active space self-consistent field (RASSCF) calculations for a systematic investigation of nature chemical bond in potassium ferrocyanide aqueous solution. The atom- site-specific RIXS excitations allow direct observation ligand-to-metal (Fe L-edge) metal-to-ligand (N K-edge) charge-transfer bands thereby evidence strong σ-donation...
Density functional theory is an efficient computational tool to investigate photophysical and photochemical processes in transition metal complexes, giving invaluable assistance interpreting spectroscopic catalytic experiments. Optimally tuned range-separated functionals are particularly promising, as they were created address some of the fundamental deficiencies present approximate exchange-correlation functionals. In this paper, we scrutinize selection optimally parameters its influence on...
The reaction pathways of bis-(2-phenylpyridinato-)(2,2'-bipyridine)iridium(III)hexafluorophosphate [Ir(ppy)2(bpy)]PF6 within a photocatalytic water reduction system for hydrogen generation based on an iron-catalyst were investigated by employing time-resolved photoluminescence spectroscopy and time-dependent density functional theory. Electron transfer (ET) from the sacrificial reagent to photoexcited Ir complex has surprisingly low probability 0.4% per collision. Hence, this step limits...
Aqueous iron(II) chloride is studied by soft X-ray absorption, emission, and resonant inelastic Raman scattering techniques on the Fe L-edge O K-edge using liquid-jet technique. Soft spectroscopies allow in situ atom-specific probing of electronic structure aqueous complex thus open door for investigation chemical bonding molecular orbital mixing. In this work, we combine theoretical ab initio restricted active space self-consistent field local atomic multiplet calculations with experimental...
Abstract L-edge soft X-ray spectroscopy has been proven to be a powerful tool unravel the peculiarities of electronic structure transition metal compounds in solution. However, absorption spectrum is often probed total or partial fluorescence yield modes, what leads inherent distortions with respect true transmission spectrum. In present work, we combine photon- and electron-yield experimental techniques multi-reference first principles calculations. Exemplified for prototypical FeCl 2...
X-ray absorption (XAS) and resonant inelastic scattering (RIXS) of a number Mn2+,3+,4+ complexes relevant for photo-electrooxidation water is studied theoretically using the RASSCF/RASSI approach. This enables us to quantify spin–orbit coupling induced mixing states with different multiplicities in valence- core-excited electronic states, evidencing mostly spin-forbidden character transitions RIXS spectra. The notably patterns spectroscopic features this series substances not only provide...
X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction molecular details requires adequate theoretical methods, which in case transition metal complexes has to account for effects due multi-configurational and spin-mixed nature many-electron wave function. Here, restricted active space self-consistent field method including spin-orbit coupling is used cope with this challenge calculate valence- core-level spectra. intensities are estimated...
The photoreduction of the bis(2-phenylpyridinato-)(2,2'-bipyridine)iridium(III) ion ([Ir(ppy)2(bpy)](+)), used as a photosensitizer in photocatalytic water splitting, by triethylamine was studied means UV/VIS, XANES, and EPR spectroscopies, supported theoretical calculations at density functional theory (DFT) complete active space self-consistent field (CASSCF/CASPT2) levels. combination these methods suggests predominant bpy localization spin-density unpaired electron with notable...
With the advancement of high harmonic generation and X-ray free-electron lasers (XFELs) to attosecond domain, studies ultrafast electron spin dynamics became possible. Yet, methods for efficient control measurement quantum state are be further developed. In this publication, we propose using magnetic scattering (MXS) resolving molecular spin-state establish a complete protocol simulate MXS diffraction patterns in molecules with ab initio chemistry based on multiconfigurational method. The...
The vertical singlet-singlet and singlet-triplet electronic excitation energies of bis(2-phenylpyridinato-)(2,2′-bipyridine)iridium(III) ([Ir(ppy)2(bpy)]+) are calculated on the basis a comparative quantum chemical study using wave function methods such as CASSCF/CASPT2 density functional theory (TDDFT) with local range-separated functionals. TDDFT results show strong dependence charge-transfer transition amount exact exchange in functional. In general, functionals provides good agreement...
Abstract Photoinduced spin‐flip in Fe II complexes is an ultrafast phenomenon that has the potential to become alternative conventional processing and magnetic storage of information. Following initial excitation by visible light into singlet metal‐to‐ligand charge‐transfer state, electronic transition high‐spin quintet state may undergo different pathways. Here we apply XUV (extreme ultraviolet) photoemission spectroscopy track low‐to‐high spin dynamics aqueous iron tris‐bipyridine complex,...
The Frenkel exciton model was adapted to describe X-ray absorption and resonant inelastic scattering spectra of polynuclear transition metal complexes by means the restricted active space self-consistent field method. proposed approach allows substantially decrease requirements on computational resources if compared a full supermolecular quantum chemical treatment. This holds true, in particular, cases where dipole approximation electronic charge density can be applied. protocol applied...
A methodology to calculate the decay rates of normal and resonant Auger processes in atoms molecules based on One-Center Approximation (OCA), using atomic radial integrals, is implemented within restricted-active-space self-consistent-field (RASSCF) multistate perturbation theory second order (MS-RASPT2) frameworks, as part OpenMolcas project. To ensure an unbiased description correlation relaxation effects initial core excited/ionized states final cationic states, their wave functions are...
We present an implementation of the Frenkel exciton model into OpenMolcas program package enabling calculations collective electronic excited states molecular aggregates based on a multiconfigurational wave function description individual monomers. The computational protocol avoids using diabatization schemes and, thus, supermolecule calculations. Additionally, use Cholesky decomposition two-electron integrals entering pair interactions enhances efficiency scheme. application method is...
Photoinduced charge transfer in transition-metal coordination complexes plays a prominent role photosynthesis and is fundamental for light-harvesting processes catalytic materials. However, revealing the relaxation pathways of separation remains very challenging task because complexity channels ultrashort time scales. Here, we employ ultrafast XUV photoemission spectroscopy to monitor fine mechanistic details electron dynamics following optical ligand-to-metal charge-transfer excitation...
In this paper we present a protocol to evaluate partial and total Auger decay rates combining the restricted active space self-consistent field electronic structure method for bound part of spectrum numerically obtained continuum orbitals in single-channel scattering theory framework. Additionally, two-step picture is employed rates. The performance exemplified prototypical neon $1s{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{-}1}3p$ resonance. Different approximations obtain orbitals, rate...
In this article the recent developments of open-source OpenMolcas chemistry software environment, since spring 2020, are described, with main focus on novel functionalities that accessible in stable branch package and/or via interfaces other packages. These community span a wide range topics computational chemistry, and presented thematic sections associated electronic structure theory, spectroscopy simulations, analytic gradients molecular optimizations, ab initio dynamics, new features....