A5035932611- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Catalytic Processes in Materials Science
- Solid-state spectroscopy and crystallography
- Catalysis and Oxidation Reactions
- Inorganic Fluorides and Related Compounds
- Machine Learning in Materials Science
- Electronic and Structural Properties of Oxides
- Quantum, superfluid, helium dynamics
- Copper-based nanomaterials and applications
- Advanced Photocatalysis Techniques
- Radioactive element chemistry and processing
- High-pressure geophysics and materials
- Chemical and Physical Properties in Aqueous Solutions
- X-ray Diffraction in Crystallography
- Gas Sensing Nanomaterials and Sensors
- Crystallography and molecular interactions
- ZnO doping and properties
- Methane Hydrates and Related Phenomena
- Photochemistry and Electron Transfer Studies
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Electrocatalysts for Energy Conversion
- Various Chemistry Research Topics
- Molecular Junctions and Nanostructures
Uppsala University
2015-2024
University of Rome Tor Vergata
2021
Stockholm University
2000-2021
University of Bath
2019
KTH Royal Institute of Technology
2000-2013
Rutherford Appleton Laboratory
2013
California Institute of Technology
2010
University of Delaware
2010
Pennsylvania State University
2010
University of Latvia
2003
In this paper we put forward the idea that various "improper, blue-shifting" hydrogen bond systems discussed in literature are all of essentially same nature and occur because three necessary circumstances: (i) presence a negative dipole moment derivative, dμ0/drXH, for isolated H-bond donor molecule; (ii) interaction between such molecule any electron density concentration on acceptor (π-system density, lone-pair ionic charge, ...) which at large intermolecular distances gives rise to...
Share Icon Twitter Facebook Reddit LinkedIn Reprints and Permissions Cite Search Site Citation Philip Coppens, Kersti Hermansson; X‐Ray Charge Densities Chemical Bonding. Physics Today 1 August 1998; 51 (8): 66–68. https://doi.org/10.1063/1.882350 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Dropdown Menu input auto suggest filter your All ContentPhysics Advanced
We examine the real space structure and electronic (particularly Ce4f electron localization) of oxygen vacancies in CeO(2) (ceria) as a function U density functional theory studies with rotationally invariant forms LDA+U GGA+U functionals. The four nearest neighbor Ce ions always relax outwards, those not carrying localized charge moving furthest. Several quantification schemes show that starts to become at approximately 3 eV degree localization reaches maximum 6 for or 5.5 GGA+U. For higher...
Abstract This roadmap presents the transformational research ideas proposed by “BATTERY 2030+,” European large‐scale initiative for future battery chemistries. A “chemistry‐neutral” to advance research, particularly at low technology readiness levels, is outlined, with a time horizon of more than ten years. The centered around six themes: 1) accelerated materials discovery platform, 2) interface genome, integration smart functionalities such as 3) sensing and 4) self‐healing processes....
Machine-learned force fields have transformed the atomistic modelling of materials by enabling simulations ab initio quality on unprecedented time and length scales. However, they are currently limited by: (i) significant computational human effort that must go into development validation potentials for each particular system interest; (ii) a general lack transferability from one chemical to next. Here, using state-of-the-art MACE architecture we introduce single general-purpose ML model,...
The structure of the hydrated calcium(II) ion in aqueous solution has been studied by means extended X-ray absorption fine spectroscopy (EXAFS), large-angle scattering (LAXS), and molecular dynamics (MD) methods. EXAFS data displayed a broad asymmetric distribution Ca−O bond distances with centroid at 2.46(2) Å. LAXS studies on four calcium halide solutions (1.5−2 mol dm-3) gave mean distance 2.46(1) This is consistent hydration number 8 determined from correlations between coordination...
To enable large-scale reactive dynamic simulations of copper oxide/water and ion/water interactions we have extended the ReaxFF force field framework to Cu/O/H interactions. this end, employed a multistage development strategy, where initial training set (containing metal/metal oxide/metal hydroxide condensed phase data [Cu(H2O)n]2+ cluster structures energies) is augmented by single-point quantum mechanices (QM) energies from clusters abstracted molecular dynamics simulation. This provides...
Abstract Highly accurate ab initio molecular dynamics (MD) methods are the gold standard for studying mechanisms in condensed phase, however, they too expensive to capture many key properties that converge slowly with respect simulation length and time scales. Machine learning (ML) approaches which reach accuracy of simulation, are, at same time, sufficiently affordable hold bridging this gap. In work we present a robust ML potential EC:EMC binary solvent, component liquid electrolytes...
Abstract For many machine learning applications in science, data acquisition, not training, is the bottleneck even when avoiding experiments and relying on computation simulation. Correspondingly, order to reduce cost carbon footprint, training efficiency key. We introduce minimal multilevel (M3L) which optimizes set sizes using a loss function at multiple levels of reference minimize combination prediction error with overall acquisition costs (as measured by computational wall-times)....
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAb Initio Study of Cooperativity in Water Chains: Binding Energies and Anharmonic FrequenciesLars Ojamaee Kersti HermanssonCite this: J. Phys. Chem. 1994, 98, 16, 4271–4282Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://pubs.acs.org/doi/10.1021/j100067a011https://doi.org/10.1021/j100067a011research-articleACS PublicationsRequest reuse permissionsArticle...
We have investigated how a neural network representation of intermolecular potential functions can be used to elevate some the problems commonly encountered during fitting and application analytical in computer simulations. For this purpose we applied feed-forward networks various sizes reproduce three-body interaction energies system H2O−Al3+−H2O. In highly polarizable terms are necessary for an accurate description system, it proved difficult fit function them. Subsequently performed Monte...
Using the DFT+U method, i.e., first principles density functional theory calculations with inclusion of on-site Coulomb interaction, effects Pd doping on O vacancy formation energy (Evac) in CeO2 has been studied. We find that Evac is lowered from 3.0eV undoped ceria to 0.6eV Pd-doped compound. Much this decrease can be attributed emerging Pd-induced gap states above valence band and below empty Ce 4f states. These localized defect involve ion its nearest neighbors, which are also main...
With the use of DFT+U method, properties Cu adsorbed on stoichiometric CeO2(111) surface, Cu-doped (denoted as Cu0.08Ce0.92O2) and CO oxidation Cu0.08Ce0.92O2 surface are studied systematically. It is found that (i) stable both an atom dopant in region. at Cu(+I) while a Cu(+II). (ii) The facilitates O-vacancy formation considerably, adsorption may suppress oxygen vacancy formation. (iii) Physisorbed CO, physisorbed CO2, well chemisorbed (carbonate) species observed contrast, clean...
The hydroxylation structural features of the first adsorption layer and its connection to proton transfer reactivity have been studied for ZnO−liquid water interface at room temperature. Molecular dynamics simulations employing ReaxFF forcefield were performed on seven ZnO surfaces with varying step concentrations. At higher coverage a level was found, in agreement previous experimental results. We also calculated free energy barrier transferring surface, showing that stepped stabilize...
Mg-doped VO2 thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < ħω 3.5 eV energy range. Clear evidence found for a widening of main band gap from 1.67 to 2.32 as Mg/(V + Mg) atomic ratio went zero 0.19, thereby significantly lowering luminous absorption. This technologically important effect could be reconciled spin-polarized density functional theory...
Polarons in metal oxides are important processes such as catalysis, high temperature superconductivity, and dielectric breakdown nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO_{2}(110), using a combination low scanning tunneling microscopy (STM), density functional theory, classical molecular dynamics calculations. We find that electrons symmetrically distributed around isolated 78 K, but is reduced, their...
Abstract Batteries and supercapacitors are electrochemical energy storage systems which involve multiple time‐scales length‐scales. In terms of the electrolyte serves as ionic conductor, a molecular‐level understanding corresponding transport phenomena, (thermal) stability interfacial properties is crucial for optimizing device performance achieving safety requirements. To this end, atomistic machine learning promising technology bridging microscopic models macroscopic phenomena. Here, we...
Abstract BATTERY 2030+ targets the development of a chemistry neutral platform for accelerating new sustainable high‐performance batteries. Here, description is given how AI‐assisted toolkits and methodologies developed in can be transferred applied to representative examples future battery chemistries, materials, concepts. This perspective highlights some main scientific technological challenges facing emerging low‐technology readiness level (TRL) chemistries concepts, specifically toolkit...
Abstract Open access to research data is increasingly important for accelerating research. Grant authorities therefore request detailed plans how managed in the projects they finance. We have recently developed such a plan EU−H2020 BIG‐MAP project—a cross‐disciplinary project targeting disruptive battery‐material discoveries. Essential reaching goal extensive sharing of across scales, disciplines and stakeholders, not limited European BATTERY 2030+ initiative but within entire battery...
Potential energy hypersurfaces (PESs) for four fluoroform complexes (with acetonitrile, ethyleneoxide, formaldehyde, and water) were explored at the HF, MP2, B3LYP/6-311++G(d,p) levels of theory. Anharmonic C–H stretching vibrational frequency shifts are reported all minima located on studied PESs. In cases, lowest-energy minimum occurs a C–H⋯O(N) hydrogen-bonded arrangement is characterized by significant blueshift (upshift), while additional [for “reversed” orientations, in which there no...
In this paper we evaluate the performance of density functional theory with B3LYP for calculations on ceria (CeO2) and cerium sesquioxide (Ce2O3). We demonstrate that is able to describe CeO2 Ce2O3 reasonably well. When compared other functionals, performs slightly better than hybrid PBE0 electronic properties but worse structural properties, although neither as well LDA+U(U=6 eV) or PBE+U(U=5 eV). also make an extensive comparison atomic basis sets suitable periodic these oxides. Here...