Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

Chemical Reviews, Journal Year: 2018, Volume and Issue: 118(15), P. 7026 - 7068

Published: May 16, 2018

Nonadiabatic mixed quantum–classical (NA-MQC) dynamics methods form a class of computational theoretical approaches in quantum chemistry tailored to investigate the time evolution nonadiabatic phenomena molecules and supramolecular assemblies. NA-MQC is characterized by partition molecular system into two subsystems: one be treated mechanically (usually but not restricted electrons) another dealt with classically (nuclei). The subsystems are connected through couplings terms enforce self-consistency. A local approximation underlies classical subsystem, implying that direct can simulated, without needing precomputed potential energy surfaces. split allows reducing costs, enabling treatment realistic systems diverse fields. Starting from three most well-established methods—mean-field Ehrenfest, trajectory surface hopping, multiple spawning—this review focuses on programs developed last 10 years. It stresses relations between their domains application. electronic structure commonly used together reviewed as well. accuracy precision simulations critically discussed, general guidelines choose an adequate method for each application delivered.

Language: Английский

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Advanced Capabilities of the PYXAID Program: Integration Schemes, Decoherence Effects, Multiexcitonic States, and Field-Matter Interaction

Journal of Chemical Theory and Computation, Journal Year: 2014, Volume and Issue: 10(2), P. 789 - 804

Published: Jan. 10, 2014

In our previous work [J. Chem. Theory Comput. 2013, 9, 4959], we introduced the PYXAID program, developed for purpose of performing nonadiabatic molecular dynamics simulations in large-scale condensed matter systems. The methodological aspects and basic capabilities program have been extensively discussed. present work, perform a thorough investigation advanced namely, integration techniques time-dependent Schrodinger equation (TD-SE), decoherence corrections via decoherence-induced surface hopping, use multiexciton basis configurations, direct simulation photoexcitation explicit light–matter interaction. We demonstrate importance mentioned features by studying electronic variety particular, that solving TD-SE may lead to significant speedup calculations provide more stable solutions. show is necessary accurate description slow relaxation processes such as electron–hole recombination solid C60. By using configurations direct, nonperturbative treatment field–matter interactions, found nontrivial optimality conditions multiple exciton generation small silicon cluster.

Language: Английский

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Nonadiabatic dynamics: The SHARC approach

Wiley Interdisciplinary Reviews Computational Molecular Science, Journal Year: 2018, Volume and Issue: 8(6)

Published: May 9, 2018

We review the Surface Hopping including ARbitrary Couplings (SHARC) approach for excited-state nonadiabatic dynamics simulations. As a generalization of popular surface hopping method, SHARC allows simulating full-dimensional molecules any type coupling terms beyond couplings. Examples these arbitrary couplings include spin-orbit or dipole moment-laser field couplings, such that can describe ultrafast internal conversion, intersystem crossing, and radiative processes. The key step consists diagonalization Hamiltonian nuclear is carried out on potential energy surfaces effects couplings-this critical in applications considering, example, transition metal complexes strong laser fields. also give an overview over new SHARC2.0 software package, released under GNU General Public License, which implements several analysis tools. closes with brief survey where was employed to study wide range molecular systems. This article categorized under: Theoretical Physical Chemistry > Reaction Dynamics KineticsSoftware Simulation MethodsSoftware Quantum Chemistry.

Language: Английский

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Recent Progress in Surface Hopping: 2011–2015

The Journal of Physical Chemistry Letters, Journal Year: 2016, Volume and Issue: 7(11), P. 2100 - 2112

Published: May 12, 2016

Developed 25 years ago, Tully's fewest switches surface hopping (FSSH) has proven to be the most popular approach for simulating quantum-classical dynamics in a broad variety of systems, ranging from gas phase, liquid and solid phases, biological nanoscale materials. FSSH is widely adopted as fundamental platform introduce modifications needed. Significant progress been made recently enhance accuracy efficiency technique. Various limitations standard FSSH-associated with quantum nuclear effects, interference decoherence, trivial or "unavoided" crossings, superexchange, representation dependence-have lifted. These advances are needed allow one treat many important phenomena chemistry, physics, materials, related disciplines. Examples include charge transport extended systems such organic solids, singlet fission molecular aggregates, Auger-type exciton multiplication, recombination relaxation dots other Auger-assisted transfer, nonradiative luminescence quenching, electron-hole recombination. This Perspective summarizes recent formulation nonadiabatic provides an outlook on future hopping.

Language: Английский

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Unravelling the Effects of Grain Boundary and Chemical Doping on Electron–Hole Recombination in CH₃NH₃PbI₃ Perovskite by Time-Domain Atomistic Simulation

Journal of the American Chemical Society, Journal Year: 2016, Volume and Issue: 138(11), P. 3884 - 3890

Published: March 1, 2016

Advancing organohalide perovskite solar cells requires understanding of carrier dynamics. Electron–hole recombination is a particularly important process because it constitutes major pathway energy and current losses. Grain boundaries (GBs) are common in methylammonium lead iodine CH3NH3PbI3 (MAPbI3) polycrystalline films. First-principles calculations have suggested that GBs little effect on the recombination; however, experiments defy this prediction. Using nonadiabatic (NA) molecular dynamics combined with time-domain density functional theory, we show notably accelerate electron–hole MAPbI3. First, enhance electron–phonon NA coupling by localizing contributing to electron hole wave functions creating additional phonon modes couple electronic degrees freedom. Second, decrease MAPbI3 bandgap, reducing number vibrational quanta needed accommodate loss. Third, phonon-induced loss coherence remains largely unchanged not accelerated, as one may expect from increased coupling. Further, replacing iodines chlorines at reduces recombination. By pushing highest occupied orbital (HOMO) away boundary, restore close value observed pristine introducing higher-frequency phonons increasing fluctuation gap, shorten coherence. Both factors compete successfully reduced bandgap relative favor long excited-state lifetimes. The simulations excellent agreement experiment characterize how chlorine dopants affect cells. suggest route photon-to-electron conversion efficiencies through rational GB passivation.

Language: Английский

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Non-adiabatic Excited-State Molecular Dynamics: Theory and Applications for Modeling Photophysics in Extended Molecular Materials

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(4), P. 2215 - 2287

Published: Feb. 10, 2020

Optically active molecular materials, such as organic conjugated polymers and biological systems, are characterized by strong coupling between electronic vibrational degrees of freedom. Typically, simulations must go beyond the Born–Oppenheimer approximation to account for non-adiabatic excited states. Indeed, dynamics is commonly associated with exciton photophysics involving charge energy transfer, well dissociation recombination. Understanding photoinduced in materials vital providing an accurate description formation, evolution, decay. This interdisciplinary field has matured significantly over past decades. Formulation new theoretical frameworks, development more efficient computational algorithms, evolution high-performance computer hardware extended these very large systems hundreds atoms, including numerous studies semiconductors biomolecules. In this Review, we will describe recent advances treatment decoherence surface-hopping methods, role solvent effects, trivial unavoided crossings, analysis data based on transition densities, implementations numerical methods. We also emphasize newly developed semiclassical approaches, Gaussian approximation, which retain phase width information significant interference effects while maintaining high efficiency approaches. The above developments have been employed successfully a variety materials.

Language: Английский

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Ab initio nonadiabatic molecular dynamics investigations on the excited carriers in condensed matter systems

Wiley Interdisciplinary Reviews Computational Molecular Science, Journal Year: 2019, Volume and Issue: 9(6)

Published: March 14, 2019

The ultrafast dynamics of photoexcited charge carriers in condensed matter systems play an important role optoelectronics and solar energy conversion. Yet it is challenging to understand such multidimensional at the atomic scale. Combining real‐time time‐dependent density functional theory with fewest‐switches surface hopping scheme, we develop ab initio nonadiabatic molecular (NAMD) code Hefei‐NAMD simulate excited carrier systems. Using this method, have investigated interfacial transfer dynamics, electron–hole recombination spin‐polarized hole different are studied energy, real momentum spaces. In addition, coupling phonons, defects adsorptions investigated. state‐of‐art NAMD studies provide unique insights This article categorized under: Structure Mechanism > Computational Materials Science Molecular Statistical Mechanics Dynamics Monte‐Carlo Methods Electronic Theory Ab Initio Software Simulation

Language: Английский

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Ultrafast Carrier Thermalization and Cooling Dynamics in Few-Layer MoS₂

ACS Nano, Journal Year: 2014, Volume and Issue: 8(10), P. 10931 - 10940

Published: Sept. 30, 2014

Femtosecond optical pump–probe spectroscopy with 10 fs visible pulses is employed to elucidate the ultrafast carrier dynamics of few-layer MoS2. A nonthermal distribution observed immediately following photoexcitation and B excitonic transitions by ultrashort, broadband laser pulse. Carrier thermalization occurs within 20 proceeds via both carrier–carrier carrier–phonon scattering, as evidenced dependence time on density sample temperature. The n–0.37±0.03 scaling suggests that equilibration non-Markovian quantum kinetics. Subsequent cooling hot Fermi–Dirac ∼0.6 ps scale scattering. Temperature- fluence-dependence studies reveal involvement phonons in process. Nonadiabatic ab initio molecular simulations, which predict scattering scales 40 0.5 ps, respectively, lend support assignment dynamics.

Language: Английский

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Quantum Coherence Facilitates Efficient Charge Separation at a MoS₂/MoSe₂ van der Waals Junction

Nano Letters, Journal Year: 2016, Volume and Issue: 16(3), P. 1996 - 2003

Published: Feb. 16, 2016

Two-dimensional transition metal dichalcogenides (MX2, M = Mo, W; X S, Se) hold great potential in optoelectronics and photovoltaics. To achieve efficient light-to-electricity conversion, electron-hole pairs must dissociate into free charges. Coulomb interaction MX2 often exceeds the charge transfer driving force, leading one to expect inefficient separation at a heterojunction. Experiments defy expectation. Using time-domain density functional theory nonadiabatic (NA) molecular dynamics, we show that quantum coherence donor-acceptor delocalization facilitate rapid MoS2/MoSe2 interface. The is larger for electron than hole, resulting longer faster transfer. Stronger NA coupling higher acceptor state accelerate further. Both hole transfers are subpicosecond, which agreement with experiments. promoted primarily by out-of-plane Mo-X modes of acceptors. Lighter S atoms, compared Se, create electrons holes. relatively slow relaxation "hot" suggests long-distance bandlike transport, observed organic recombination notably across interface isolated MoS2 MoSe2, favoring long-lived separation. atomistic, studies provide valuable insights excitation dynamics two-dimensional dichalcogenides.

Language: Английский

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Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface

Nano Letters, Journal Year: 2017, Volume and Issue: 17(10), P. 6435 - 6442

Published: Sept. 15, 2017

The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary general expectation, electron-hole can occur vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast transfer between neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead direct tunneling, interlayer hole strongly promoted an adiabatic mechanism phonon excitation occurring on 20 fs, which good agreement with experiment. atomic level picture phonon-assisted revealed our study valuable both for fundamental understanding carrier at heterointerfaces as well design novel quasi-2D devices optoelectronic photovoltaic applications.

Language: Английский

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