Dynamics of recombination <i>via</i> conical intersection in a semiconductor nanocrystal

Peng, Wei Tao; Fales, B. Scott; Shu, Yinan; Levine, Bernard B.

doi:10.1039/c7sc04221c

Cited by 28 publications

(45 citation statements)

References 78 publications

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“…It is well established that the ultrafast nonradiative relaxation of molecules often occurs at conical intersections (CIs), points of degeneracy between potential energy surfaces (PES). , Upon passage through such CIs, electronic energy is converted into vibrational energy along specific branching modes, which lift the degeneracy between PESs. These modes promote the progress of a photochemical reaction toward a particular product following nonradiative decay. , CIs associated with surface defect sites have been implicated in the nonradiative recombination of semiconductor nanocrystals, and the role of branching modes in driving the nonradiative recombination dynamics in silicon dangling bond defects has been explored …”

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confidence: 99%

Vibronic Excitons and Conical Intersections in Semiconductor Quantum Dots

Tilluck

Hetherington

et al. 2021

J. Phys. Chem. Lett.

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Surface defects and organic surface-capping ligands affect the photoluminescence properties of semiconductor quantum dots (QDs) by altering the rates of competing nonradiative relaxation processes. In this study, broadband two-dimensional electronic spectroscopy reveals that absorption of light by QDs prepares vibronic excitons, excited states derived from quantum coherent mixing of the core electronic and ligand vibrational states. Rapidly damped coherent wavepacket motions of the ligands are observed during hot-carrier cooling, with vibronic coherence transferred to the photoluminescent state. These findings suggest a many-electron, molecular theory for the electronic structure of QDs, which is supported by calculations of the structures of conical intersections between the exciton potential surfaces of a small ammonia-passivated model CdSe nanoparticle.

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confidence: 99%

Vibronic Excitons and Conical Intersections in Semiconductor Quantum Dots

Tilluck

Hetherington

et al. 2021

J. Phys. Chem. Lett.

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“…where and denote the electronic and nuclear equation of motion from κSE, as given in eqs 12 and 21, and where the additional terms are decay-of-mixing (DM) terms, which are explained in detail elsewhere. 48,53 In tCSDM decoherence contribution to the change in the nuclear momentum is 53 (24) in which is the decoherence time, K is the pointer state, and is the decoherence vector for states I and K given by (25) where is the internal vibrational momentum, and a0 ≡ 1 bohr.…”

Section: Theorymentioning

confidence: 99%

“…1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19 Recent advances on these topics have enabled quantitative accurate simulations for medium-size molecules and qualitatively accurate simulations for nano-sized molecules or clusters. 20,21,22,23,24,25,26,27,28,29,30,31 The electronic structure must be treated quantum mechanically, and for simulating all but the smallest systems, one uses a semiclassical treatment of nuclear motion. The present article is concerned with direct dynamics, where, instead of requiring parametrized analytic functions for the energies and couplings, all required energies, forces, and couplings for each geometry that is important for evaluating dynamical properties are obtained directly from electronic structure calculations when they are needed in the dynamics calculation.…”

Section: Introductionmentioning

confidence: 99%

Nonadiabatic Dynamics Algorithms with Only Potential Energies and Gradients: Curvature-Driven Coherent Switching with Decay of Mixing and Curvature-Driven Trajectory Surface Hopping

Shu

Zhang

Sun

et al. 2021

Preprint

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Direct dynamics by mixed quantum–classical nonadiabatic methods is an important tool for understanding processes involving multiple electronic states. Very often, the computational bottleneck of such direct simulation comes from electronic structure theory. For example, at every time step of a trajectory, nonadiabatic dynamics requires potential energy surfaces, their gradients, and the matrix elements coupling the surfaces. The need for the couplings can be alleviated by employing the time derivatives of the wave functions, which can be evaluated from overlaps of electronic wave functions at successive timesteps. However, evaluation of overlap integrals is still expensive for large systems. In addition, for electronic structure methods for which the wave functions or the coupling matrix elements are not available, nonadiabatic dynamics algorithms become inapplicable. In this work, building on recent work by Baeck and An, we propose new nonadiabatic dynamics algorithms that only require adiabatic potential energies and their gradients. The new methods are named curvature- driven coherent switching with decay of mixing (κCSDM) and curvature-driven trajectory surface hopping (κTSH). We show how powerful these new methods are in terms of computer time and good agreement with methods employing nonadiabatic coupling vectors computed in conventional ways. The lowering of the computational cost will allow longer nonadiabatic trajectories and greater ensemble averaging to be affordable, and the ability to calculate the dynamics without electronic structure coupling matrix elements extends the dynamics capability to new classes of electronic structure methods.

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“…[41][42][43][44] For the truly multiconfigurational approaches, the computational cost is enormous and these techniques are not readily used to study interfacial electronic structure (though see recent work of Levine et al for an interesting CAS calculation of dangling bonds on a silicon cluster). 56 At this point, it should be clear to the reader that strong approximations will be necessary in order to practically and robustly solve for the electronic structure of a molecule reacting on a metal surface, while capturing enough correlation energy for even qualitative (and ideally quantitative) accuracy. In order to achieve such a goal, in this paper, we will follow a three-pronged approach.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure for Multielectronic Molecules Near a Metal Surface

Chen

Jin

Dou

et al. 2020

Preprint

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We analyze a model problem representing a multi-electronic molecule sitting on a metal surface. Working with a reduced configuration interaction Hamiltonian, we show that one can extract very accurate ground state wavefunctions as compared with the numerical renormalization group theory (NRG) -even in the limit of weak metal-molecule coupling strength but strong intramolecular electron-electron repulsion. Moreover, we extract what appear to be meaningful excitation energies as well. Our findings should lay the groundwork for future ab initio studies of charge transfer processes and bond making/breaking processes on metal surfaces.

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Dynamics of recombination via conical intersection in a semiconductor nanocrystal

Abstract: The ultrafast dynamics of nonradiative recombination at dangling bond defects is elucidated by nanoscale multireference ab initio molecular dynamics simulations.

Cited by 28 publications

References 78 publications

Vibronic Excitons and Conical Intersections in Semiconductor Quantum Dots

Vibronic Excitons and Conical Intersections in Semiconductor Quantum Dots

Nonadiabatic Dynamics Algorithms with Only Potential Energies and Gradients: Curvature-Driven Coherent Switching with Decay of Mixing and Curvature-Driven Trajectory Surface Hopping

Electronic Structure for Multielectronic Molecules Near a Metal Surface

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