1
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Berkinsky DB, Proppe AH, Utzat H, Krajewska CJ, Sun W, Šverko T, Yoo JJ, Chung H, Won YH, Kim T, Jang E, Bawendi MG. Narrow Intrinsic Line Widths and Electron-Phonon Coupling of InP Colloidal Quantum Dots. ACS NANO 2023; 17:3598-3609. [PMID: 36758155 DOI: 10.1021/acsnano.2c10237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
InP quantum dots (QDs) are the material of choice for QD display applications and have been used as active layers in QD light-emitting diodes (QDLEDs) with high efficiency and color purity. Optimizing the color purity of QDs requires understanding mechanisms of spectral broadening. While ensemble-level broadening can be minimized by synthetic tuning to yield monodisperse QD sizes, single QD line widths are broadened by exciton-phonon scattering and fine-structure splitting. Here, using photon-correlation Fourier spectroscopy, we extract average single QD line widths of 50 meV at 293 K for red-emitting InP/ZnSe/ZnS QDs, among the narrowest for colloidal QDs. We measure InP/ZnSe/ZnS single QD emission line shapes at temperatures between 4 and 293 K and model the spectra using a modified independent boson model. We find that inelastic acoustic phonon scattering and fine-structure splitting are the most prominent broadening mechanisms at low temperatures, whereas pure dephasing from elastic acoustic phonon scattering is the primary broadening mechanism at elevated temperatures, and optical phonon scattering contributes minimally across all temperatures. Conversely for CdSe/CdS/ZnS QDs, we find that optical phonon scattering is a larger contributor to the line shape at elevated temperatures, leading to intrinsically broader single-dot line widths than for InP/ZnSe/ZnS. We are able to reconcile narrow low-temperature line widths and broad room-temperature line widths within a self-consistent model that enables parametrization of line width broadening, for different material classes. This can be used for the rational design of more spectrally narrow materials. Our findings reveal that red-emitting InP/ZnSe/ZnS QDs have intrinsically narrower line widths than typically synthesized CdSe QDs, suggesting that these materials could be used to realize QDLEDs with high color purity.
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Affiliation(s)
- David B Berkinsky
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Andrew H Proppe
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hendrik Utzat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chantalle J Krajewska
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Weiwei Sun
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tara Šverko
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jason J Yoo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heejae Chung
- Samsung Advanced Institute of Technology, Samsung Electronics, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Yu-Ho Won
- Samsung Advanced Institute of Technology, Samsung Electronics, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Taehyung Kim
- Samsung Advanced Institute of Technology, Samsung Electronics, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Eunjoo Jang
- Samsung Advanced Institute of Technology, Samsung Electronics, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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2
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Li QQ, Yan L, Chu W, He J, Luo H, Frauenheim T, Tretiak S, Zhou L. Control of Polaronic Behavior and Carrier Lifetimes via Metal and Anion Alloying in Chalcogenide Perovskites. J Phys Chem Lett 2022; 13:4955-4962. [PMID: 35639456 DOI: 10.1021/acs.jpclett.2c00880] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Transition-metal perovskite chalcogenides (TMPCs) have emerged as lead-free alternatives to lead-halide perovskites and have been currently of increasing interest for optoelectronic applications because of their suitable band gaps, high carrier mobility, strong light absorption, and high stability. Here, we systematically report a study on the effects of Ti- and Se-alloying strategies on polaron behavior and carrier lifetimes in nonradiative recombination. Although such alloying can effectively tune the band gap of BaZrS3, we observe localized small polaron formation upon Ti alloying and large polarons generating in Se alloying. Ti-alloying strengthens the electron-phonon coupling, leading to a reduced carrier lifetime. Remarkably, Se-alloying weakens the electron-phonon coupling and prolongs the nonradiative electron-hole recombination lifetime by up to 60% compared to that in pristine BaZrS3 material. The simulations rationalize the difference in carrier lifetimes in TMPC alloys and provide guidelines for further improvements in TMPC-based photoelectronic devices.
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Affiliation(s)
- Qiao-Qiao Li
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Luo Yan
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, Zhejiang 313001, P. R. China
| | - Weibin Chu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, Fudan University, Shanghai 200433, P. R. China
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Junjie He
- Bremen Center for Computational Materials Science, University of Bremen, Bremen 28359, Germany
- Department of Physical and Macromolecular Chemistry & Charles University Centre of Advanced Materials, Faculty of Science, Charles University in Prague, Hlavova 8, Prague 12843, Czech Republic
| | - Huanbo Luo
- Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006, P. R. China
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science, University of Bremen, Bremen 28359, Germany
- Beijing Computational Science Research Center (CSRC), Beijing 100193, P. R. China
- Shenzhen Computational Science and Applied Research (CSAR) Institute, Shenzhen 518110, P. R. China
| | - Sergei Tretiak
- Theoretical Division, Center for Nonlinear Studies, and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Liujiang Zhou
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, Zhejiang 313001, P. R. China
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3
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Agrawal S, Vasenko AS, Trivedi DJ, Prezhdo OV. Charge carrier nonadiabatic dynamics in non-metal doped graphitic carbon nitride. J Chem Phys 2022; 156:094702. [DOI: 10.1063/5.0079085] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Graphitic carbon nitride (GCN) has attracted significant attention due to its excellent performance in photocatalytic applications. Non-metal doping of GCN has been widely used to improve the efficiency of the material as a photocatalyst. Using a combination of time-domain density functional theory with nonadiabatic molecular dynamics, we study the charge carrier dynamics in oxygen and boron doped GCN systems. The reported simulations provide a detailed time-domain mechanistic description of the charge separation and recombination processes that are of fundamental importance while evaluating the photovoltaic and photocatalytic performance of the material. The appearance of smaller energy gaps due to the presence of dopant states improves the visible light absorption range of the doped systems. At the same time, the nonradiative lifetimes are shortened in the doped systems as compared to the pristine GCN. In the case of boron doped at a carbon (B–C–GCN), the charge recombination time is very long as compared to the other two doped systems owing to the smaller electron–phonon coupling strength between the valence band maximum and the trap state. The results suggest B–C–GCN as the most suitable candidate among three doped systems studied in this work for applications in photocatalysis. This work sheds light into the influence of dopants on quantum dynamics processes that govern GCN performance and, thus, guides toward building high-performance devices in photocatalysis.
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Affiliation(s)
- Sraddha Agrawal
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey S. Vasenko
- HSE University, 101000 Moscow, Russia
- I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Dhara J. Trivedi
- Department of Physics, Clarkson University, Potsdam, New York 13699, USA
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
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4
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Liu XY, Xie XY, Fang WH, Cui G. Photoinduced relaxation dynamics of nitrogen-capped silicon nanoclusters: a TD-DFT study. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1433335] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Xiang-Yang Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Xiao-Ying Xie
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
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5
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Peng WT, Fales BS, Shu Y, Levine BG. Dynamics of recombination via conical intersection in a semiconductor nanocrystal. Chem Sci 2018; 9:681-687. [PMID: 29629136 PMCID: PMC5869574 DOI: 10.1039/c7sc04221c] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/13/2017] [Indexed: 12/17/2022] Open
Abstract
Conical intersections are well known to introduce nonradiative decay pathways in molecules, but have only recently been implicated in nonradiative recombination processes in materials. Here we apply excited state ab initio molecular dynamics simulations based on a multireference description of the electronic structure to defective silicon nanocrystals up to 1.7 nm in diameter to search for accessible nonradiative recombination pathways. Dangling bond defects are found to induce conical intersections between the ground and first excited electronic states of five systems of various sizes. These defect-induced conical intersections are accessible at energies that are in the visible range (2.4-2.7 eV) and very weakly dependent on particle size. The dynamic simulations suggest that these intersections are accessed 40-60 fs after creation of a defect-localized excitation. This ultrafast recombination is attributed to the fact that Jahn-Teller distortion on the first excited state drives the defect directly towards a conical intersection with the ground electronic state.
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Affiliation(s)
- Wei-Tao Peng
- Department of Chemistry , Michigan State University , East Lansing , MI 48824 , USA .
| | - B Scott Fales
- Department of Chemistry , The PULSE Institute , Stanford University , Stanford , CA 94305 , USA.,SLAC National Accelerator Laboratory , Menlo Park , CA 94025 , USA
| | - Yinan Shu
- Department of Chemistry , University of Minnesota , Minneapolis , MN 55455 , USA
| | - Benjamin G Levine
- Department of Chemistry , Michigan State University , East Lansing , MI 48824 , USA .
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6
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Pal S, Nijjar P, Frauenheim T, Prezhdo OV. Atomistic Analysis of Room Temperature Quantum Coherence in Two-Dimensional CdSe Nanostructures. NANO LETTERS 2017; 17:2389-2396. [PMID: 28234486 DOI: 10.1021/acs.nanolett.6b05368] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Recent experiments on CdSe nanoplatelets synthesized with precisely controlled thickness that eliminates ensemble disorder have allowed accurate measurement of quantum coherence at room temperature. Matching exactly the CdSe cores of the experimentally studied particles and considering several defects, we establish the atomistic origins of the loss of coherence between heavy and light hole excitations in two-dimensional CdSe and CdSe/CdZnS core/shell structures. The coherence times obtained using molecular dynamics based on tight-binding density functional theory are in excellent agreement with the measured values. We show that a long coherence time is a consequence of both small fluctuations in the energy gap between the excited state pair, which is much less than thermal energy, and a slow decay of correlation between the energies of the two states. Anionic defects at the core/shell interface have little effect on the coherence lifetime, while cationic defects strongly perturb the electronic structure, destroying the experimentally observed coherence. By coupling to the same phonon modes, the heavy and light holes synchronize their energy fluctuations, facilitating long-lived coherence. We further demonstrate that the electronic excitations are localized close to the surface of these narrow nanoscale systems, and therefore, they couple most strongly to surface acoustic phonons. The established features of electron-phonon coupling and the influence of defects, surfaces, and core/shell interfaces provide important insights into quantum coherence in nanoscale materials in general.
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Affiliation(s)
- Sougata Pal
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Parmeet Nijjar
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science, Universität Bremen , Otto-Hahn-Alle 1, 28359 Bremen, Germany
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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7
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Mallus MI, Aghtar M, Chandrasekaran S, Lüdemann G, Elstner M, Kleinekathöfer U. Relation between Dephasing Time and Energy Gap Fluctuations in Biomolecular Systems. J Phys Chem Lett 2016; 7:1102-1108. [PMID: 26950038 DOI: 10.1021/acs.jpclett.6b00134] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Excitation energy and charge transfer are fundamental processes in biological systems. Because of their quantum nature, the effect of dephasing on these processes is of interest especially when trying to understand their efficiency. Moreover, recent experiments have shown quantum coherences in such systems. As a first step toward a better understanding, we studied the relationship between dephasing time and energy gap fluctuations of the individual molecular subunits. A larger set of molecular simulations has been investigated to shed light on this dependence. This set includes bacterio-chlorophylls in Fenna-Matthews-Olson complexes, the PE545 aggregate, the LH2 complexes, DNA, photolyase, and cryptochromes. For the individual molecular subunits of these aggregates it has been confirmed quantitatively that an inverse proportionality exists between dephasing time and average gap energy fluctuation. However, for entire complexes including the respective intermolecular couplings, such a relation still needs to be verified.
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Affiliation(s)
- Maria Ilaria Mallus
- Department of Physics and Earth Sciences, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany
| | - Mortaza Aghtar
- Department of Physics and Earth Sciences, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany
| | | | - Gesa Lüdemann
- Institute of Physical Chemistry, Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany
| | - Marcus Elstner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany
| | - Ulrich Kleinekathöfer
- Department of Physics and Earth Sciences, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany
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8
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Liu J, Prezhdo OV. Chlorine doping reduces electron-hole recombination in lead iodide perovskites: time-domain ab initio analysis. J Phys Chem Lett 2015; 6:4463-4469. [PMID: 26505613 DOI: 10.1021/acs.jpclett.5b02355] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Rapid development in lead halide perovskites has led to solution-processable thin film solar cells with power conversion efficiencies close to 20%. Nonradiative electron-hole recombination within perovskites has been identified as the main pathway of energy losses, competing with charge transport and limiting the efficiency. Using nonadiabatic (NA) molecular dynamics, combined with time-domain density functional theory, we show that nonradiative recombination happens faster than radiative recombination and long-range charge transfer to an acceptor material. Doping of lead iodide perovskites with chlorine atoms reduces charge recombination. On the one hand, chlorines decrease the NA coupling because they contribute little to the wave functions of the valence and conduction band edges. On the other hand, chlorines shorten coherence time because they are lighter than iodines and introduce high-frequency modes. Both factors favor longer excited-state lifetimes. The simulation shows good agreement with the available experimental data and contributes to the comprehensive understanding of electronic and vibrational dynamics in perovskites. The generated insights into design of higher-efficiency solar cells range from fundamental scientific principles, such as the role of electron-vibrational coupling and quantum coherence, to practical guidelines, such as specific suggestions for chemical doping.
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Affiliation(s)
- Jin Liu
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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9
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Liu J, Kilina SV, Tretiak S, Prezhdo OV. Ligands Slow Down Pure-Dephasing in Semiconductor Quantum Dots. ACS NANO 2015; 9:9106-9116. [PMID: 26284384 DOI: 10.1021/acsnano.5b03255] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is well-known experimentally and theoretically that surface ligands provide additional pathways for energy relaxation in colloidal semiconductor quantum dots (QDs). They increase the rate of inelastic charge-phonon scattering and provide trap sites for the charges. We show that, surprisingly, ligands have the opposite effect on elastic electron-phonon scattering. Our simulations demonstrate that elastic scattering slows down in CdSe QDs passivated with ligands compared to that in bare QDs. As a result, the pure-dephasing time is increased, and the homogeneous luminescence line width is decreased in the presence of ligands. The lifetime of quantum superpositions of single and multiple excitons increases as well, providing favorable conditions for multiple excitons generation (MEG). Ligands reduce the pure-dephasing rates by decreasing phonon-induced fluctuations of the electronic energy levels. Surface atoms are most mobile in QDs, and therefore, they contribute greatly to the electronic energy fluctuations. The mobility is reduced by interaction with ligands. A simple analytical model suggests that the differences between the bare and passivated QDs persist for up to 5 nm diameters. Both low-frequency acoustic and high-frequency optical phonons participate in the dephasing processes in bare QDs, while low-frequency acoustic modes dominate in passivated QDs. The theoretical predictions regarding the pure-dephasing time, luminescence line width, and MEG can be verified experimentally by studying QDs with different surface passivation.
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Affiliation(s)
- Jin Liu
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Svetlana V Kilina
- Department of Chemistry, North Dakota State University , Fargo, North Dakota 58108, United States
| | - Sergei Tretiak
- Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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10
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Trivedi DJ, Prezhdo OV. Decoherence Allows Model Reduction in Nonadiabatic Dynamics Simulations. J Phys Chem A 2015. [PMID: 26221974 DOI: 10.1021/acs.jpca.5b05869] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A nonadiabatic (NA) molecular dynamics (MD) simulation requires calculation of NA coupling matrix elements, the number of which scales as a square of the number of basis states. The basis size can be huge in studies of nanoscale materials, and calculation of the NA couplings can present a significant bottleneck. A quantum-classical approximation, NAMD overestimates coherence in the quantum, electronic subsystem, requiring decoherence correction. Generally, decoherence times decrease with increasing energy separation between pairs of states forming coherent superpositions. Since rapid decoherence stops quantum dynamics, one expects that decoherence-corrected NAMD can eliminate the need for calculation of NA couplings between energetically distant states, notably reducing the computational cost. Considering several types of dynamics in a semiconductor quantum dot, we demonstrate that indeed, decoherence allows one to reduce the number of needed NA coupling matrix elements. If the energy levels are spaced closer than 0.1 eV, one obtains good results while including only three nearest-neighbor couplings, and in some cases even with just the first nearest-neighbor coupling scheme. If the energy levels are spaced by about 0.4 eV, the nearest-neighbor model fails, while three or more nearest-neighbor schemes also provide good results. In comparison, the results of NAMD simulation without decoherence vary continuously with changes in the number of NA couplings. Thus, decoherence effects induced by coupling to a quantum-mechanical environment not only provide the physical mechanism for NAMD trajectory branding and improve the accuracy of NAMD simulations, but also afford significant computational savings.
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Affiliation(s)
- Dhara J Trivedi
- †Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, United States
| | - Oleg V Prezhdo
- ‡Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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11
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Kilina S, Kilin D, Tretiak S. Light-Driven and Phonon-Assisted Dynamics in Organic and Semiconductor Nanostructures. Chem Rev 2015; 115:5929-78. [DOI: 10.1021/acs.chemrev.5b00012] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Svetlana Kilina
- Chemistry
and Biochemistry Department, North Dakota State University, Fargo, North Dakota 5810, United States
| | - Dmitri Kilin
- Department
of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, United States
| | - Sergei Tretiak
- Theoretical
Division, Center for Nonlinear Studies (CNLS) and Center for Integrated
Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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