scholarly journals Exploring the effects of quantum decoherence on the excited-state dynamics of molecular systems

2021 ◽  
Vol 140 (4) ◽  
Author(s):  
Eric R. Heller ◽  
Jan-Ole Joswig ◽  
Gotthard Seifert
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Density Functional ◽  
Bond Cleavage ◽  
Minimum Energy ◽  
Quantum Decoherence ◽  
Ensemble Averaging ◽  
Excited State Dynamics ◽  
Complete Active Space ◽  
Related Compounds

AbstractFewest-switches surface hopping (FSSH) is employed in order to investigate the nonadiabatic excited-state dynamics of thiophene and related compounds and hence to establish a connection between the electronic system, the critical points in configuration space and the deactivation dynamics. The potential-energy surfaces of the studied molecules were calculated with complete active space self-consistent field and time-dependent density-functional theory. They are analyzed thoroughly to locate and optimize minimum-energy conical intersections, which are essential to the dynamics of the system. The influence of decoherence on the dynamics is examined by employing different decoherence schemes. We find that irrespective of the employed decoherence algorithm, the population dynamics of thiophene give results which are sound with the expectations grounded on the analysis of the potential-energy surface. A more detailed look at single trajectories as well as on the excited-state lifetimes, however, reveals a substantial dependence on how decoherence is accounted for. In order to connect these findings, we describe how ensemble averaging cures some of the overcoherence problems of uncorrected FSSH. Eventually, we identify carbon–sulfur bond cleavage as a common feature accompanying electronic transitions between different states in the simulations of all thiophene-related compounds studied in this work, which is of interest due to their relevance in organic photovoltaics.

Photoinduced bond cleavage in CH3ReO3: excited state dynamics

2008 ◽  
Vol 32 (11) ◽  
pp. 1904 ◽  
Author(s):  
Paulo Jorge Costa ◽  
Maria José Calhorda ◽  
Sébastien Villaume ◽  
Chantal Daniel
Keyword(s):  
Excited State ◽  
Bond Cleavage ◽  
Excited State Dynamics

scholarly journals An Efficient First-Principles Saddle Point Searching Method Based on Distributed Kriging Metamodels

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Anh Tran ◽  
Lijuan He ◽  
Yan Wang
Keyword(s):  
Potential Energy ◽  
Saddle Point ◽  
Density Functional ◽  
Materials Science ◽  
Mean Squared Error ◽  
Dimensional Space ◽  
Minimum Energy ◽  
Saddle Points ◽  
Computational Materials ◽  
Searching Method

Searching for local minima, saddle points, and minimum energy paths (MEPs) on the potential energy surface (PES) is challenging in computational materials science because of the complexity of PES in high-dimensional space and the numerical approximation errors in calculating the potential energy. In this work, a local minimum and saddle point searching method is developed based on kriging metamodels of PES. The searching algorithm is performed on both kriging metamodels as the approximated PES and the calculated one from density functional theory (DFT). As the searching advances, the kriging metamodels are further refined to include new data points. To overcome the dimensionality problem in classical kriging, a distributed kriging approach is proposed, where clusters of data are formed and one metamodel is constructed within each cluster. When the approximated PES is used during the searching, each predicted potential energy value is an aggregation of the ones from those metamodels. The dimension of each metamodel is further reduced based on the observed symmetry in materials systems. The uncertainty associated with the ground-state potential energy is quantified using the statistical mean-squared error in kriging to improve the robustness of the searching method.

scholarly journals Hydrogen transfer reaction: Bond formation and bond cleavage through the eyes of interacting quantum atoms

2019 ◽  
Vol 84 (8) ◽  
pp. 891-900
Author(s):  
Branislav Milovanovic ◽  
Mihajlo Etinski ◽  
Milena Petkovic
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Minimum Energy ◽  
Fragment Analysis ◽  
Interacting Quantum Atoms ◽  
Methoxy Radical ◽  
The One

Hydrogen transfer from hydroquinone to the methoxy radical was studied using the density functional theory. The energy decomposition technique, interacting quantum atoms, was employed for a detailed investigation of the changes that the bonds of interest go through along the minimum energy path in the vicinity of the transition state. The whole system was divided either into two or three fragments. The two-fragment analysis enabled investigation of the bond that is formed or the one that is cleaved by defining the fragments as reactants and as products, respectively. The three-fragment analysis (the fragments being semiquinone, hydrogen atom and methoxy radical) was used for the simultaneous analysis of the two phenomena, bond cleavage and bond formation. Additionally, it enabled the interaction between the particle that donates the hydrogen atom and the one that accepts it to be investigated. This interaction is characterized by attractive non-classical and repulsive classical interactions. It was demonstrated that the transferring hydrogen atom undergoes the most pronounced energy changes and gives the largest contribution to the deformation energy.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3904
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed.

Theoretical investigation on ESIPT mechanism for a novel Sal-3,4-benzophen system

2017 ◽  
Vol 16 (08) ◽  
pp. 1750073 ◽  
Author(s):  
Jian Lv ◽  
Dapeng Yang
Keyword(s):  
Excited State ◽  
Hydrogen Bonds ◽  
Potential Energy ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
Potential Energy Curves ◽  
State Process ◽  
The Density Functional Theory ◽  
Intramolecular Hydrogen ◽  
Excited State Process

In this work, we theoretically investigate the properties of excited state process for a novel salicylidene sal-3,4-benzophen (Sal-3,4-B) system, which contains two intramolecular hydrogen bonds (O1-H2[Formula: see text]N3 and O4-H5[Formula: see text]N6). Based on the density functional theory (DFT) and time-dependent DFT (TDDFT) methods, we find these two hydrogen bonds should be strengthened in the S1 state, while the O4-H5[Formula: see text]N6 one could be largely affected upon the excitation process. Analyses about infrared (IR) vibrational spectra about hydrogen bond moieties also confirm this viewpoint. Frontier molecular orbitals (MOs) depict the nature of electronic excited state and support the excited state intramolecular proton transfer (ESIPT) reaction.Two kinds of stepwise potential energy curves of Sal-3,4-B in the S1 state demonstrate that only one proton could be transferred. Also based on constructing potential energy curves, the synergetic situation could be eliminated. Due to the specific ESIPT mechanism for Sal-3,4-B, we successfully explain the previous experiment and provide a reasonable attribution to the second emission peak of experiment.

scholarly journals Density functional theory study of the Jahn-Teller effect in cobaltocene

2009 ◽  
Vol 81 (8) ◽  
pp. 1397-1411 ◽  
Author(s):  
Matija Zlatar ◽  
Carl-Wilhelm Schläpfer ◽  
Emmanuel Penka Fowe ◽  
Claude A. Daul
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Functional ◽  
Energy Surface ◽  
Minimum Energy ◽  
Normal Modes ◽  
Coupling Coefficients ◽  
Functional Theory ◽  
Jahn Teller

A detailed discussion of the potential energy surface of bis(cyclopentadienyl)cobalt(II), cobaltocene, is given. Vibronic coupling coefficients are calculated using density functional theory (DFT). Results are in good agreement with experimental findings. On the basis of our calculation there is no second-order Jahn–Teller (JT) effect as predicted by group theory. The JT distortion can be expressed as a linear combination of all totally symmetric normal modes of the low-symmetry, minimum-energy conformation. The out-of-plane ring deformation is the most important mode. The JT distortion is analyzed by seeking the path of minimal energy of the adiabatic potential energy surface.

Sign in / Sign up

Export Citation Format

Share Document