A5028296163- Spectroscopy and Quantum Chemical Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Photosynthetic Processes and Mechanisms
- Enzyme Structure and Function
- Electron and X-Ray Spectroscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Photochemistry and Electron Transfer Studies
- Free Radicals and Antioxidants
- Spectroscopy and Laser Applications
- Scientific Computing and Data Management
- Metal-Catalyzed Oxygenation Mechanisms
- Semiconductor Quantum Structures and Devices
- Chemical Thermodynamics and Molecular Structure
- Magnetism in coordination complexes
- Photoreceptor and optogenetics research
- Atmospheric Ozone and Climate
- Advanced Thermodynamics and Statistical Mechanics
- Mass Spectrometry Techniques and Applications
- Lanthanide and Transition Metal Complexes
- Thermal and Kinetic Analysis
- Advanced X-ray Imaging Techniques
- Adhesion, Friction, and Surface Interactions
- finance, banking, and market dynamics
- Characterization and Applications of Magnetic Nanoparticles
KTH Royal Institute of Technology
1998-2024
AlbaNova
2018-2024
Stockholm University
2018-2024
SLAC National Accelerator Laboratory
2016-2021
Heidelberg University
2018-2021
University of Nottingham
2018
Linköping University
2012-2016
In oxygenic photosynthesis, light-driven oxidation of water to molecular oxygen is carried out by the oxygen-evolving complex (OEC) in photosystem II (PS II). Recently, we reported room-temperature structures PS four (semi)stable S-states, S
Abstract In natural photosynthesis, the light-driven splitting of water into electrons, protons and molecular oxygen forms first step solar-to-chemical energy conversion process. The reaction takes place in photosystem II, where Mn 4 CaO 5 cluster stores four oxidizing equivalents, S 0 to intermediate states Kok cycle, sequentially generated by photochemical charge separations center then catalyzes O–O bond formation chemistry 1–3 . Here, we report room temperature snapshots serial...
Based on an asymmetric Lanczos-chain subspace algorithm, damped coupled cluster linear response functions have been implemented for the hierarchy of (CC) models including CC with single excitations (CCS), CC2, and double (CCSD), CCSD noniterative triple corrected excitation energies CCSDR(3). This work is a first step toward extension these theoretical electronic structure methods well-established high accuracy in UV-vis absorption spectroscopies to applications concerned x-ray radiation....
We present an implementation of the damped coupled-cluster linear response function based on asymmetric Lanczos chain algorithm for hierarchy approximations CCS (coupled-cluster singles), CC2 singles and approximate doubles), CCSD doubles). Triple corrections to excitation energies can be included via CCSDR(3) doubles with noniterative-triples-corrected energies) approximation. The performance some potentialities approach are investigated in calculations visible/ultraviolet absorption...
We report the observation and analysis of gain curve amplified Kα x-ray emission from solutions Mn(II) Mn(VII) complexes using an free electron laser to create 1s core-hole population inversion. find spectra at amplification levels extending over 4 orders magnitude until saturation. observe bandwidths below Mn lifetime broadening in onset stimulated emission. In exponential regime resolution corrected spectral width ∼1.7 eV FWHM is constant 3 magnitude, pointing buildup transform limited...
The performance of several standard and popular approaches for calculating X-ray absorption spectra at the carbon, nitrogen, oxygen K-edges 40 primarily organic molecules up to size guanine has been evaluated, focusing on low-energy intense 1s → π* transitions. Using results obtained with CVS-ADC(2)-x fc-CVS-EOM-CCSD as benchmark references, we investigate CC2, ADC(2), ADC(3/2), commonly adopted density functional theory (DFT)-based approaches. Here, focus is precision rather than accuracy...
Near carbon K-edge X-ray absorption fine structure spectra of a series fluorine-substituted ethenes and acetone have been studied using coupled cluster density functional theory (DFT) polarization propagator methods, as well the static-exchange (STEX) approach. With complex (CPP) implemented in theory, relaxation effects following excitation core electrons are accounted for terms electron correlation, enabling systematic convergence these with respect to excitations operator. Coupled results...
Soluble methane monooxygenase (sMMO) is a multicomponent metalloenzyme that catalyzes the conversion of to methanol at ambient temperature using nonheme, oxygen-bridged dinuclear iron cluster in active site. Structural changes hydroxylase component (sMMOH) containing diiron caused by complex formation with regulatory (MMOB) and reduction are important for regulation O
For the calculation of core-excited states probed through X-ray absorption spectroscopy, core-valence separation (CVS) scheme has become a vital tool. This approach allows to target such with high specificity, albeit introducing an error. We report implementation post-processing step for CVS excitations obtained within algebraic-diagrammatic construction polarisation propagator (ADC), which removes this Based on we provide detailed analysis scheme, identifying its accuracy be dominated by...
Complementary XFEL methods reveal O 2 reaction intermediates and global protein dynamics during Isopenicillin N synthase catalysis.
The impact of the Tamm-Dancoff approximation (TDA) for time-dependent density functional theory (TDDFT) calculations X-ray absorption and emission spectra (XAS XES) is investigated, showing small discrepancies in excitation energies intensities. Through explicit diagonalization TDDFT Hessian, XES was considered by using full with a core-hole reference state. This has previously not been possible most implementations as result presence negative eigenvalues. Furthermore, core-valence...
A systematic design procedure for a high flux solar simulator is presented in this paper. The 84 kWe based on an array of 12 commercially available xenon-arc lamps (each 7 kWe) coupled with silicone-on-glass Fresnel lenses as the optical concentrator. ray-tracing model xenon lamp has been developed real emitter shape and lens optics; simulations performed using non-sequential Monte Carlo technique have validated against experimental test data. results show that 19.7 kW radiative power...
Serial femtosecond crystallography (SFX) using the ultrashort X-ray pulses from a free-electron laser (XFEL) provides new way of collecting structural data at room temperature that allows for following reaction in real time after initiation. XFEL experiments are conducted shot-by-shot mode as sample is destroyed and replenished each pulse, therefore, monitoring controlling quality by situ diagnostic tools critical. To study metalloenzymes, we developed use simultaneous collection diffraction...
A computational benchmark study on X-ray absorption spectra of water has been performed by means transition-potential density functional theory (TP-DFT), damped time-dependent (TDDFT), and coupled cluster (CC) linear response theory. For liquid water, using TDDFT with a tailored CAM-B3LYP polarizable embedding, we find that an embedding over 2000 molecules is required to fully converge spectral features for individual molecules, but substantially smaller can be used within averaging schemes....
The connection between specific features in the water X-ray absorption spectrum and emission (XES) local H-bond coordination is studied based on structures obtained from path-integral molecular dynamics simulations using either opt-PBE-vdW density functional or MB-pol force field. Computing XES all molecules a snapshot results only one peak lone-pair (1b1) region, while experiment shows two peaks separated by 0.8-0.9 eV. Different configurations were classified structure index (LSI)...
The calculation of X-ray emission spectra has been addressed with the algebraic diagrammatic construction (ADC) scheme, using a core-ionized wave function as reference state. With this, valence-to-core transitions are found first eigenstates negative eigenvalues. performance ADC hierarchical methods ADC(2), ADC(2)-x, and ADC(3/2) investigated on 17 transition second-row elements (C, N, O, F, Ne), 5 third-row (S Cl). We report ADC(2) results within 0.20 ± 0.36 eV experimental values an...
X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means damped four-component density functional response theory.
The eChem project features an e-book published as a web page (10.30746/978-91-988114-0-7), collecting repository of Jupyter notebooks developed for the dual purpose explaining and exploring theory underlying computational chemistry in highly interactive manner well providing tutorial-based presentation complex workflows needed to simulate embedded molecular systems real biochemical and/or technical interest. For students ranging from beginners advanced users, book is suited self-directed...
The water oxidation reaction in photosystem II (PS II) produces most of the molecular oxygen atmosphere, which sustains life on Earth, and this process releases four electrons protons that drive downstream CO
Abstract ADC‐connect ( adcc ) is a hybrid python / C++ module for performing excited state calculations based on the algebraic‐diagrammatic construction scheme polarization propagator (ADC). Key design goal to restrict this single purpose and facilitate connection external packages, example, obtaining Hartree–Fock references, plotting spectra, or modeling solvents. Interfaces four self‐consistent field codes have already been implemented, namely pyscf , psi4 molsturm veloxchem . The...