A5060807266- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Laser Applications
- Mass Spectrometry Techniques and Applications
- Muon and positron interactions and applications
- Chemical Reactions and Isotopes
- Semiconductor materials and interfaces
- Organic Electronics and Photovoltaics
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Electron and X-Ray Spectroscopy Techniques
- Molecular Spectroscopy and Structure
- Graphene research and applications
- Advancements in Battery Materials
- Photonic Crystals and Applications
- Semiconductor materials and devices
- Atomic and Molecular Physics
- Photoreceptor and optogenetics research
- Quantum optics and atomic interactions
- Silicon and Solar Cell Technologies
- Conducting polymers and applications
- Organic Light-Emitting Diodes Research
- Laser-Matter Interactions and Applications
- Molecular spectroscopy and chirality
University of Bristol
2018-2024
University of Leeds
2014-2024
Saratov State University
2019
National University of Quilmes
2019
Consejo Nacional de Investigaciones Científicas y Técnicas
2019
Center for Integrated Nanotechnologies
2019
Los Alamos National Laboratory
2019
University of Oxford
2010
University of California, Davis
2006
Université de Montréal
2003-2005
We present a new algorithm for ab initio quantum nonadiabatic molecular dynamics that combines the best features of Multiple Spawning (AIMS) and Multiconfigurational Ehrenfest (MCE) methods. In this method, multiple cloning (AIMC), individual trajectory basis functions (TBFs) follow equations motion (as in MCE). However, set is expanded AIMS) when these TBFs become sufficiently mixed, preventing prolonged evolution on an averaged potential energy surface. refer to expansion as “cloning,”...
The Multiconfigurational Ehrenfest (MCE) method is a quantum dynamics technique which allows treatment of large number nuclear degrees freedom. This paper presents review MCE and its recent applications, providing summary the formalisms, including ab initio direct versions also giving results. Firstly, we describe version 2 (MCEv2) applicability to report new calculations show that approach converges exact result in model systems with tens Secondly, previous "on fly" Multiple Cloning...
We report a detailed computational simulation of the photodissociation pyrrole using <italic>ab initio</italic> Multiple Cloning (AIMC) method implemented within MOLPRO.
We present NEXMD version 2.0, the second release of (Nonadiabatic EXcited-state Molecular Dynamics) software package. Across a variety new features, v2.0 incorporates implementations two hybrid quantum-classical dynamics methods, namely, Ehrenfest (EHR) and Ab-Initio Multiple Cloning sampling technique for Multiconfigurational quantum (MCE-AIMC or simply AIMC), which are alternative options to previously implemented trajectory surface hopping (TSH) method. To illustrate these methodologies,...
Photoinduced dynamics of electronic and vibrational unidirectional energy transfer between <italic>meta</italic>-linked building blocks in a phenylene ethynylene dendrimer is simulated using multiconfigurational Ehrenfest time-dependent diabatic basis (MCE-TDDB) method.
Direct atomistic simulation of nonadiabatic molecular dynamics is a challenging goal that allows important insights into fundamental physical phenomena. A variety frameworks, ranging from fully quantum treatment nuclei to semiclassical and mixed quantum–classical approaches, were developed. These algorithms are then coupled specific electronic structure techniques. Such diversity lack standardized implementation make it difficult compare the performance different methodologies when treating...
We present the result of our calculations ultrafast electron diffraction (UED) for cyclobutanone excited into S2 electronic state, which is based on non-adiabatic dynamics simulations with Ab Initio Multiple Cloning (AIMC) method structure calculated at SA(3)-CASSCF(12,12)/aug-cc-pVDZ level theory. The key features in UED pattern were identified, can be used to distinguish between reaction pathways observed AIMC dynamics, although there a significant overlap representative signals due...
Singlet exciton localization in conformationally disordered poly(3-hexylthiophene) (P3HT) is investigated via configuration interaction (singles) calculations of the Pariser-Parr-Pople model. The P3HT structures are generated by molecular dynamics simulations. lowest-lying excitons spatially localized, space filling, and nonoverlapping. These define spectroscopic segments or chromophores. strong conformational disorder causes breaks pi-conjugation. Depending on relative values...
Using density-functional-theory calculations, we have identified new stable configurations for tri-, tetra-, and pentavacancies in silicon. These consist of combinations a ring hexavacancy with three, two, or one interstitial atoms, respectively, such that all atoms remain fourfold. As result, their formation energies are lower by 0.6, 1.0, 0.6 eV, than the "part hexagonal ring" configurations, believed until now to be lowest-energy states.
Exciton localization in conjugated polymers with weak conformational disorder is investigated via the Anderson model Gaussian off-diagonal disorder, $\ensuremath{\sigma}$. We show that a small fraction of low-energy eigenstates are spatially localized, nonoverlapping, and space filling. term these states ``local exciton ground states'' (LEGS). The LEGS exhibit an almost density states, average length $L\ensuremath{\sim}{\ensuremath{\sigma}}^{\ensuremath{-}2/3}$, inhomogeneous optical...
Multidimensional wave function: a superposition of Gaussian coherent states guided by Ehrenfest trajectories suited to clone and swap their electronic amplitudes.
We present an account of our recent effort to improve simulation the photodissociation small heteroaromatic molecules using <italic>Ab Initio</italic> Multiple Cloning (AIMC) algorithm. The ultimate goal is create a quantitative and converged technique for fully quantum simulations which treats both electrons nuclei on level. calculate analyse total kinetic energy release (TKER) spectra Velocity Map Images (VMI), compare results directly with experimental measurements. In this work, we...
The process of dissociation for two hydrofluorocarbon molecules in low triplet states excited by electron impact plasma is investigated ab initio molecular dynamics (AIMD). interest the hydrofluorocarbons motivated their role etching microelectronic technologies. Dissociation very fast, and reaction products can be predicted. In this work, it was found that higher relax into lowest state within a few femtoseconds due to nonadiabatic dynamics, such simplest MD on seems give reasonable...
The efficiency of the intramolecular energy transfer in light harvesting dendrimers is determined by their well-defined architecture with high degree order. After photoexcitation, through-space and through-bond mechanisms can take place, involving vectorial exciton migration among different chromophores within dendrimer highly branched structures. Their inherent gradient depends on how multiple chromophoric units have been assembled, subject to inter-connects, spatial distances,...
Motivated by the reported enhanced singlet exciton yield in light-emitting polymers, we investigate spin-orbit coupling between Coulombically bound interchain excitations. We show theoretically that because of close similarity and triplet wave functions, these states is negligible. Using density matrix renormalization group calculations on model systems, confirm theoretical predictions: typically ${10}^{3}--{10}^{4}$ times smaller than corresponding intramolecular states, being ca....
We present a simple way to incorporate molecule-field interaction into non-adiabatic molecular dynamics. This makes possible integrated simulation of the photoexcitaion and ensuing photodynamics, providing accurate initial conditions that are specific for particular wave-length duration laser pulse. The proposed approach is applied simulate dynamics pyrrole photodissociation. particularly convenient use with ab initio Multiple Cloning approach, but idea can be implemented in other quantum methods.
The protonation state of His291 in cytochrome c oxidase (CcO), a ligand to the CuB center enzyme, has been recently studied this group by using combined density functional theory (DFT)/electrostatic (QM/MM) calculations. On basis these calculations, model proton pumping mechanism CcO proposed. Due certain technical difficulties, procedure used previous calculation find partial atomic charges QM system for solvation energy evaluation was not entirely satisfactory; i.e., it self-consistent....
The ultrafast photodissociation dynamics of 2-ethylpyrrole (2-EP) is simulated in a fully quantum manner on the S1 and S2 πσ* states by ab initio multiple cloning (AIMC) method. AIMC treats electrons with accurate electronic structure methods "on fly", nuclear wavefunction propagation via basis set Ehrenfest trajectory guided Gaussian wavepackets. Total kinetic energy release (TKER) spectra are produced, as well velocity map images N-H dissociation times. These compared to results from...
Energy transfer in multichromophoric molecules can be affected by coherences that are induced the electronic and vibrational couplings between chromophore units. Coherent electron-vibrational dynamics persist at subpicosecond time scale even room temperature. Furthermore, wave-like localized-delocalized motions of wave function modulated vibrations actively participate intermolecular energy process. Herein, nonadiabatic excited state molecular simulations have been performed on a rigid...
Isotherms for the liquid-gas phase transition in silicon have been calculated using isothermal-isobaric (NPT) Monte Carlo simulations with atom-atom interactions described by Stillinger-Weber potential. In order to permit high-performance calculations, a procedure has developed compute efficiently changes potential energy resulting from one-atom moves; method is applicable and other potentials separable three-body terms. For silicon, critical temperature, pressure density found be...
The positron lifetimes for various vacancy clusters in silicon are calculated within the framework of two-component electron-positron density functional theory. effect trapped on electron and relaxation structure is investigated. Our calculations show that, contrary to usual assumption, positron-induced forces do not compensate general electronic inward forces. Thus, geometry optimization required order determine lifetime accurately. For monovacancy divacancy, results our good agreement with...
The paper presents a comprehensive study of the physicochemical and electrochemical properties new nano-microporous non-woven composite separation material for lithium-ion battery based on nano- microfibers polyvinylidene fluoride (PVDF) its copolymer with polytetrafluoroethylene (PTFE), obtained by capillary-less electrospinning. A technique synthesis was developed, composition polymeric solution electrospinning conditions were optimized to produce polymer nano-microfibers required...
Fully quantum nonadiabatic dynamics calculation of photodissociation azoles shows good agreement with experiment and foreshadows the predictive ability method.
Photo-dissociation dynamics is simulated for vibrationally pre-excited pyrrole molecules using an ab initio multiple cloning approach. Total kinetic energy release (TKER) spectra and dissociation times are calculated. It found that pre-excitation of N–H bond vibrations facilitates fast direct dissociation, which results in a significant increase the high-energy wing TKER spectra. The very good agreement with recent mediated photo-dissociation experiment, where spectrum was measured excited...