Structure, intermolecular interactions, and dynamic properties of NTO crystal with impurity defects: A computational study

CrystEngComm ◽  
2021 ◽  
Author(s):  
Jincheng Ji ◽  
Kun Wang ◽  
Simin Zhu ◽  
Weihua Zhu
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Electronic Properties ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Computational Study ◽  
Dynamic Properties ◽  
Tight Binding ◽  
Dynamical Properties ◽  
Impurity Defects

Density functional tight binding (DFTB) method and DFTB-based molecular dynamics (DFTB-MD) were employed to study the crystal structure, electronic properties, intermolecular interactions, and dynamical properties of the impurity-contained β-NTO (3-nitro-1,2,4-triazole-5-one)...

Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized Metalloid Gold Nanoclusters from Ehrenfest dynamics.

2021 ◽  
Author(s):  
Adrian Dominguez-Castro ◽  
Thomas Frauenheim
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Gold Nanoclusters ◽  
Tight Binding ◽  
Time Dependent ◽  
Effective Strategy ◽  
Dynamics Simulations ◽  
Dependent Density

Theoretical calculations are an effective strategy to comple- ment and understand experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach...

Diamond {111} Surface: Graphitization or Reconstruction?

1995 ◽  
Vol 383 ◽  
Author(s):  
G. Jungnickel ◽  
D. Porezag ◽  
Th. Frauenheim ◽  
W. R. L. Lambrecht ◽  
B. Segall ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Density Functional ◽  
Tight Binding ◽  
Diamond Growth ◽  
Functional Theory ◽  
Surface Phases ◽  
Surface Graphitization

ABSTRACTThe reconstruction of the diamond {1111} surface is re-examined by means of density functional theory based tight-binding molecular dynamics. Evidence is found for competition between a graphitizing tendency leading to an unreconstructed but relaxed 1 × 1 surface and a π-bonded chain-like 2 × 1 reconstruction. The implications of the possible co-existence of these two distinct surface phases for diamond growth are discussed.

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF TRANSITION METAL DI-CHALCOGENIDES (MX2) M=(Mo, W) AND X=(S, Se) IN BULK STATE: A FIRST-PRINCIPLES STUDY

2017 ◽  
Vol 22 (1) ◽  
pp. 41-50
Author(s):  
Ram Prasad Sedhain ◽  
Gopi Chandra Kaphle
Keyword(s):  
Transition Metal ◽  
Electronic Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Calculated Data ◽  
Modern Technology ◽  
Fundamental Aspect ◽  
Bulk State ◽  
Error Bar ◽  
Structural And Electronic Properties

Transition metal di-chalcogenides (MX2) M=(Mo, W) and X=(S, Se) in bulk state are of great interest due to their diverse applications in the field of modern technology as well as to understand the fundamental aspect of Physics. We performed structural and electronic properties of selected systems using density functional theory implemented in Tight Binding Linear Muffin- tin Orbital (TBLMTO) approach with subsequent refinement. The structural optimization is performed through energy minimization process and lattice parameters of optimized structures for MoS2, MoSe2, WS2 and WSe2 are found to be 3.20Å, 3.34Å, 3.27Å and 3.34Å respectively, which are within the error bar less than 5% with experimental values. The band gaps for all TMDCs are found to be of indirect types with semiconducting behaviours. The values of band gap of MoS2, MoSe2, WS2 and WSe2 in bulk state are found to be 1.16eV, 108eV, 1.50eV and 1.29eV respectively which are comparable with experimental and previously calculated data. Due to the symmetric nature of up spin and down spin channels of Density of States (DOS) all the systems selected are found to be non magnetic. However it fully supports the results obtained from band structure calculations. The potential and charge distributions plots support the results. The charge density plots reveals the covalent nature of bond in (100) plane. However (110) plane shows mixed types of bonding.Journal of Institute of Science and TechnologyVolume 22, Issue 1, July 2017, page: 41-50

Mechanisms and kinetics of initial pyrolysis and combustion reactions of 1,1-diamino-2,2-dinitroethylene from density functional tight-binding molecular dynamics simulations

2019 ◽  
Vol 97 (11) ◽  
pp. 795-804 ◽  
Author(s):  
Dong Xiang ◽  
Weihua Zhu
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Density Functional ◽  
Tight Binding ◽  
Combustion Process ◽  
Exponential Factor ◽  
Three Stages ◽  
Dynamics Simulations ◽  
Combustion Processes ◽  
Kinetics Of

The density functional tight-binding molecular dynamics approach was used to study the mechanisms and kinetics of initial pyrolysis and combustion reactions of isolated and multi-molecular FOX-7. Based on the thermal cleavage of bridge bonds, the pyrolysis process of FOX-7 can be divided into three stages. However, the combustion process can be divided into five decomposition stages, which is much more complex than the pyrolysis reactions. The vibrations in the mean temperature contain nodes signifying the formation of new products and thereby the transitions between the various stages in the pyrolysis and combustion processes. Activation energy and pre-exponential factor for the pyrolysis and combustion reactions of FOX-7 were obtained from the kinetic analysis. It is found that the activation energy of its pyrolysis and combustion reactions are very low, making both take place fast. Our simulations provide the first atomic-level look at the full dynamics of the complicated pyrolysis and combustion process of FOX-7.

scholarly journals Molecular Insights into Cage Occupancy of Hydrogen Hydrate: A Computational Study

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 699 ◽  
Author(s):  
Ma ◽  
Zhong ◽  
Liu ◽  
Zhong ◽  
Yan ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Storage ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Storage Capacity ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Hydrogen Storage Capacity ◽  
Large Cage ◽  
Dynamics Simulations

Density functional theory calculations and molecular dynamics simulations were performed to investigate the hydrogen storage capacity in the sII hydrate. Calculation results show that the optimum hydrogen storage capacity is ~5.6 wt%, with the double occupancy in the small cage and quintuple occupancy in the large cage. Molecular dynamics simulations indicate that these multiple occupied hydrogen hydrates can occur at mild conditions, and their stability will be further enhanced by increasing the pressure or decreasing the temperature. Our work highlights that the hydrate is a promising material for storing hydrogen.

scholarly journals Effect of Point Defects on Electronic Properties and Structure of Talc (001) Surface by First Principles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 69
Author(s):  
Xindi Ma ◽  
Huicong Du ◽  
Ping Lan ◽  
Jianhua Chen ◽  
Lihong Lan
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Surface States ◽  
State Density ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Impurity Atoms ◽  
Electron State Density ◽  
Calculation Results ◽  
Impurity Defects

The surface structure and electronic properties of Mg vacancy defects on talc (001) and impurity defects with Fe, Mn, Ni, Al, and Ca replacing Mg atoms were calculated by using density functional theory. The calculation results show that the order of impurity substitution energy is Mn < Ni < Al < Ca < Fe. This indicates that Fe impurity defects are most easily formed in talc crystals. The covalent bonding between Si atoms and reactive oxygen atoms adjacent to impurity atoms is weakened and the ionic property is enhanced. The addition of Fe, Mn, and Ni atoms makes the surface of talc change from an insulator to a semiconductor and enhances its electrical conductivity. The analysis of electron state density shows that surface states composed of impurity atoms 4S orbital appear near the Fermi level.

scholarly journals Hydration Dependent Band Gap Tunability of Self-Assembled Phenylalanine-Tryptophan Nanotubes

2020 ◽  
Author(s):  
Hugo Souza ◽  
Antonio Chaves Neto ◽  
Francisco Sousa ◽  
Rodrigo Amorim ◽  
Alexandre Reily Rocha ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Building Block ◽  
Density Functional ◽  
Tight Binding ◽  
Water Molecules ◽  
Confined Water ◽  
Functional Theory ◽  
Tight Binding Method

In this work, we investigate the effects of building block separation of Phenylalanine-Tryptophan nanotube induced by the confined water molecules on the electronic properties using density-functional theory based tight-binding method. <div><br></div>

scholarly journals Multiscale QM/MM Molecular Dynamics Simulations of the Trimeric Major Light-Harvesting Complex II

2021 ◽  
Author(s):  
Sayan Maity ◽  
Vangelis Daskalakis ◽  
Marcus Elstner ◽  
Ulrich Kleinekathöfer
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Chlorophyll A ◽  
Density Functional ◽  
Light Harvesting ◽  
Higher Plants ◽  
Tight Binding ◽  
Spectral Densities ◽  
Light Harvesting Complex ◽  
Dynamics Simulations

Photosynthetic processes are driven by sunlight. Too little of it and the photosynthetic machinery cannot produce the reductive power to drive the anabolic pathways. Too much sunlight and the machinery can get damaged. In higher plants, the major Light Harvesting Complex (LHCII) efficiently absorbs the light energy, but can also dissipate it when in excess (quenching). In order to study the dynamics related to the quenching process but also the exciton dynamics in general, one needs to accurately determine the so-called spectral density which describes the coupling between the relevant pigment modes and the environmental degrees of freedom. To this end, Born–Oppenheimer molecular dynamics simulations in a quantum mechanics/molecular mechanics (QM/MM) fashion utilizing the density functional based tight binding (DFTB) method have been performed for the ground state dynamics. Subsequently, the time-dependent extension of the long-range-corrected DFTB scheme has been employed for the excited state calculations of the individual chlorophyll-a molecules in the LHCII complex. The analysis of this data resulted in spectral densities showing an astonishing agreement with the experimental counterpart in this rather large system. This consistency with an experimental observable also supports the accuracy, robustness, and reliability of the present multi-scale scheme. In addition, the resulting spectral densities and site energies were used to determine the exciton transfer rate within a special pigment pair consisting of a chlorophyll-a and a carotenoid molecule which is assumed to play a role in the balance between the light harvesting and quenching modes.

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