A5032851146- Advanced Chemical Physics Studies
- Molecular Spectroscopy and Structure
- Quantum, superfluid, helium dynamics
- Astrophysics and Star Formation Studies
- Experimental Learning in Engineering
- High-pressure geophysics and materials
- Catalysis and Oxidation Reactions
- Astro and Planetary Science
- E-Learning and Knowledge Management
- Machine Learning in Materials Science
- Various Chemistry Research Topics
- Atmospheric chemistry and aerosols
- Innovative Teaching Methods
- Genetics, Bioinformatics, and Biomedical Research
- Spacecraft Design and Technology
- Fluorine in Organic Chemistry
- Cold Atom Physics and Bose-Einstein Condensates
- Multicomponent Synthesis of Heterocycles
- Oxidative Organic Chemistry Reactions
- Radical Photochemical Reactions
- Advanced Condensed Matter Physics
- Crystal Structures and Properties
- Planetary Science and Exploration
- Scientific Research and Discoveries
- Luminescence and Fluorescent Materials
Scientific Computing & Modelling (Netherlands)
2014-2025
Leiden University
2007-2014
Vrije Universiteit Amsterdam
2014
Institute of Theoretical Physics
2014
University College London
2007-2010
The structure and surface energies of the cleaved, reconstructed, fully hydroxylated (001) alpha-quartz various thicknesses are investigated with periodic density functional theory (DFT). properties cleaved reproduced a slab thickness 18 atomic layers, while thicker 27-layer is necessary for reconstructed surface. performance hybrid DFT B3LYP, using an basis set, compared generalised gradient approximation, PBE, employing plane waves. Both methodologies give similar structures surfaces,...
Experimental phosphorescent lifetimes for various organometallic complexes are well reproduced by spin–orbit coupling TDDFT calculations with a continuum solvation model.
We implemented and compared four algorithms to locate instantons, i.e., the most likely tunneling paths at a given temperature. These allow calculate reaction rates, including atom tunneling, down very low An instanton is first-order saddle point of Euclidean action in space closed Feynman paths. Newton-Raphson method partitioned rational function optimization (P-RFO) algorithm, dimer method, newly proposed mode-following where unstable mode directly estimated from path. tested on three...
Abstract Climate Change and Materials Criticality challenges are driving urgent responses from global governments. These drive policy to achieve sustainable, resilient, clean solutions with Advanced (AdMats) for industrial supply chains economic prosperity. The research landscape comprising industry, academe, government identified a critical path accelerate the Green Transition far beyond slow conventional through Digital Technologies that harness Artificial Intelligence, Smart Automation...
The formation of water in the interstellar medium from hydrogen and oxygen atoms on a pristine olivine surface (forsterite (010)) is investigated with an embedded cluster approach. 55-atom quantum described at density functional level while remaining 1629 are atomistic potentials. Transition states most easily calculated our modified implementation climbing-image nudged elastic band method ChemShell. With these computational techniques, we find that gas phase can chemisorb (−102 kJ mol−1)...
Dust particles, ubiquitous throughout the Universe, continuously evolve in processes closely entangled with stellar life cycle. nucleates outflows of dying stars and is heavily processed journey through interstellar medium, until it finally subsumed a next-generation star or its surrounding planetary system. Although formation silicates has been studied experimentally theoretically for decades, stardust nucleation process condensation zone oxygen-rich still remains mysterious. These are...
Cosmic cat.: Tunneling effects in the reaction between hydrogen atoms and benzene have been studied with a new direct dynamics implementation of harmonic quantum transition-state theory. In certain regions interstellar space, tunneling could facilitate H chemisorption on polycyclic aromatic hydrocarbons, thereby catalyzing HD H2 formation.
The formation of CO 2 in the gas phase and on a polyaromatic hydrocarbon surface (coronene) via three possible pathways is investigated with density functional theory.Calculations show that coronene catalyses model grain surfaces.The addition 3 O to activated by 2530 K phase.This barrier lowered 253 for Eley-Rideal mechanism 952 hot-atom coronene.Alternative are HCO radical, followed dissociation intermediate.The + barrierless more than sufficiently exothermic subsequently cleave H-C...
We calculate, down to low temperature and for different isotopes, the reaction rate constants hydrogen abstraction H + H3COH → H2 CH2OH/CH3O. These explain known abundances of deuterated forms methanol in interstellar clouds, where CH2DOH can be almost as abundant CH3OH. For from both C- O-end methanol, barrier-crossing motion involves movement light atoms. Consequently, tunneling plays a dominant role already at relatively high temperature. Our implementation harmonic quantum transition...
In this paper, we present the Amsterdam Modeling Suite (AMS), a comprehensive software platform designed to support advanced molecular and materials simulations across wide range of chemical physical systems. AMS integrates cutting-edge quantum methods, including Density Functional Theory (DFT) time-dependent DFT, with mechanics, fluid thermodynamics, machine learning techniques, more, enable multi-scale modeling complex Its design philosophy allows for seamless coupling between components,...
The importance of tunnelling in the formation CO2 from O(3P) + CO at very low temperatures is studied with harmonic quantum transition state theory. To optimize state, we have used both fitted potential energy surfaces and direct dynamics, where forces energies are calculated by a chemistry code on fly as they needed. Whilst does increase classical reaction rate for addition temperatures, onset too to significantly contribute interstellar CO2. Instead, it more likely that an oxygen atom...
Abstract Photolysis of a series E or Z stereoisomeric α‐R‐substituted bromostyrenes (R = CH 3 , F CN) in methanol yields and/or styrenes, which stem from the corresponding vinyl radicals. The results show that α‐Me radical is rapidly equilibrating, bent structure, while α‐F stable species, agreement with earlier thermal results. α‐CN assigned as inverting and not linear species stereochemical function temperature. Stereochemical data for α‐C(H)=O system diethyl ether indicate product forming...
The formation of H2 on a pristine olivine surface [forsterite (010)] is investigated computationally. Calculations show that the forsterite catalyzes by providing chemisorption sites for H atoms. route allows stepwise release reaction exothermicity and stronger coupling to surface, which increases efficiency energy dissipation. This suggests formed should be much less rovibrationally excited than graphite surface. Gas-phase atoms impinging will first physisorb relatively strongly (Ephys=...
The chemisorption of hydrogen atoms on polycyclic aromatic hydrocarbons (PAHs) is studied at low temperatures via quantum mechanical tunnelling through reaction barriers. PAHs are ubiquitous in the interstellar medium and may exist various charge states as well hydrogenation states. have been suggested to catalyze H2 formation photon-dominated regions chemisorbed atoms. Hydrogenated also implicated by relative strengths infrared bands protoplanetary nebulae, reflection nebulae H ii regions....
Tunnelling plays a crucial role in the low-temperature chemistry interstellar medium (ISM), particular for reactions involving hydrogen atoms. Using harmonic quantum transition state theory we studied reaction rates down to 20 K including tunnelling effects gas phase of formaldehyde with atoms, paying attention isotope effects. Hydrogen atoms can either add formaldehyde, yielding methoxy radical which is ultimately hydrogenated form methanol, or they subtract atom, could provide route...
Studies aiming to understand the physicochemical properties of interstellar dust and chemical reactions that occur on in it have traditionally been preserve astronomical observation experimental attempts mimic astronomically relevant conditions laboratory. Increasingly, computational modelling its various guises is establishing a complementary third pillar support this endeavour by providing detailed insights into complexities chemistry. Inherently, basis be found details (e.g. atomic...
The COVID-19 pandemic disrupted chemistry teaching practices globally as many courses were forced online, necessitating adaptation to the digital platform. biggest impact was practical component of curriculum—the so-called wet lab. Naively, it would be thought that computer-based laboratories have little problem in making move. However, this is not case there are unrecognized differences between delivering in-person and virtually: software issues, technology, classroom management....
Although it is often assumed that the stereochemistry in Ugi multicomponent reactions determined final Mumm rearrangement step, experimental and computational evidence on hydroxylated pyrrolines proceed under kinetic control reported. The of reaction established with addition isocyanide to intermediate iminium ion, whose conformation by its substitution pattern.
The reactivity of the thermodynamically stable nanopyroxene cluster Mg4Si4O12 towards hydrogen and oxygen atoms is studied. Quantum chemical calculations reveal that it can adsorb without a barrier, which could catalyze H2 formation. Furthermore, if we consider consecutive atom adsorption, take up to equivalent four units water (2H + O) before molecular starts form preferentially. resulting superoxygenated nanosilicate (Mg4Si4H4O16) contains only hydroxyl groups has high oxygen-to-metal...
Dust particles are quintessential for the chemical evolution of Universe. nucleates in stellar outflows dying stars and subsequently travels through interstellar medium, continuously evolving via energetic processing, collisions condensation. Finally, dust incorporated next-generation star or its surrounding planetary system. In oxygen-rich outflows, silicates observed condensation zone (1200-1000 K), but, spite several decades experimental theoretical study, stardust nucleation process...
The sequential addition of H atoms to CO adsorbed on a siliceous edingtonite surface is studied with an embedded cluster approach, using density functional theory for the quantum mechanical (QM) and molecular force field (MM) cluster. With this setup, calculated QM/MM adsorption energies are in agreement previous calculations employing periodic boundary conditions. catalytic effect (100) hydrogenation assessed because its relevance astrochemistry. While silanol group hydroxylated did not...
The formation of carbonyl sulphide, OCS, is investigated computationally on a model carbonaceous grain surface (coronene) using density functional theory. Four reaction pathways for the OCS are investigated: from CO + S (on both singlet and triplet surfaces) HS, CS O (again OH. Langmuir−Hinshelwood, Eley−Rideal, hot-atom mechanisms investigated. Calculations show that all species in ground state physisorbed surface. However, sulfur oxygen their first excited states chemisorb coronene....
The specific catalytic effect of a silica grain on the formation methanol via sequential addition H atoms to CO adsorbed surface is investigated. A negatively charged defect siliceous edingtonite found reduce gas phase barriers for + COads and H2C=Oads reactions by 770 399 K, respectively, when compared same in phase. sites could also be applicable hydrogenation other unsaturated species. However, activation energies are still too large (1150 2230 K) CH3OH form efficiently at 10–20 K...
Astral-Katalyse: Der Tunneleffekt bei der Reaktion von Wasserstoffatomen mit Benzol wird einer neuen Anwendung harmonischer Quantenübergangszustandstheorie basierend auf direkter Dynamik untersucht. In manchen Bereichen des Weltraums kann die Chemisorption Wasserstoff polycyclischen aromatischen Kohlenwasserstoffen und damit Bildung HD H2 erleichtern.