Effects of Defect on Ferroelectric Stability in PbTiO3 Thin Films

MRS Advances ◽  
2016 ◽  
Vol 1 (5) ◽  
pp. 363-368 ◽  
Author(s):  
Lin Zhu ◽  
Jeong Ho You ◽  
Jinghong Chen
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Dft Calculations ◽  
Spontaneous Polarization ◽  
Density Functional ◽  
Defect Density ◽  
Induced Field ◽  
Dynamics Simulations ◽  
Strain Modeling ◽  
Charged Point Defect

ABSTRACTEffects of defect on ferroelectric stability in PbTiO3 (PTO) thin films have been investigated using molecular dynamics with first-principles effective Hamiltonian. In this paper, oxygen vacancy (Vo) has been considered to study the hysteresis loop, spontaneous polarization as a function of film thickness. Vo has been modeled as a charged point defect. Density functional theory (DFT) calculations are performed to determine the Vo-induced localized fields (both mechanical and electrical) and the calculated DFT results are used as inputs to molecular dynamics simulations in a large system. The strain field induced by the Vo is calculated by DFT calculations and fitted by the continuum strain modeling, and the electrostatic field is given by the superposition of the Vo-induced field and the external field. Vo significantly reduces the spontaneous polarization and increases the critical thickness.

Combined Virtual Screening, DFT Calculations and Molecular Dynamics Simulations to Discovery of Potent MMP-9 Inhibitors

2019 ◽  
Vol 16 (8) ◽  
pp. 892-903
Author(s):  
Hamed Bahrami ◽  
Hafezeh Salehabadi ◽  
Zahra Nazari ◽  
Massoud Amanlou
Keyword(s):  
Molecular Dynamics ◽  
Binding Energy ◽  
Virtual Screening ◽  
Dft Calculations ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Docking Studies ◽  
Binding Energies ◽  
Energy Calculations ◽  
Dynamics Simulations

Background: Matrix metalloproteinase-9 (MMP-9) plays a crucial role in the development and progression of cancer. Therefore, identifying its inhibitors has enjoyed numerous attentions. In this report, a hybrid approach, including pharmacophore-based virtual screening, docking studies, and density functional theory (DFT) binding energy calculations followed by molecular dynamics simulations, was used to identify potential MMP-9 inhibitors. Methods: Pharmacophore modeling based on ARP101, as a known MMP-9 inhibitor, was performed and followed by virtual screening of ZINC database and docking studies to introduce a set of new ligands as candidates for potent inhibitors of MMP-9. The binding energies of MMP-9 and the selected ligands as well as ARP101, were estimated via the DFT energy calculations. Subsequently, molecular dynamics simulations were applied to evaluate and compare the behavior of ARP101 and the selected ligand in a dynamic environment. Results: (S,Z)-6-(((2,3-dihydro-1H-benzo[d]imidazol-2-yl)thio)methylene)-2-((4,6,7- trimethylquinazolin- 2-yl)amino)-1,4,5,6-tetrahydropyrimidin-4-ol, ZINC63611396, with the largest DFT binding energy, was selected as a proper potent MMP-9 inhibitor. Molecular dynamics simulations indicated that the new ligand was stable in the active site. Conclusion: The results of this study revealed that compared to the binding energies achieved from the docking studies, the binding energies obtained from the DFT calculations were more consistent with the intermolecular interactions. Also, the interaction between the Zinc ion and ligand, in particular the Zn2+-ligand distance, played a profound role in the quantity of DFT binding energies.

Graphene adlayer growth between nonepitaxial graphene and Ni(111) substrate: a promising theoretical scheme

2020 ◽  
Author(s):  
Lijuan Meng ◽  
Jinlian Lu ◽  
Yujie Bai ◽  
Lili Liu ◽  
Tang Jingyi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Chemical Vapor Deposition ◽  
Molecular Dynamics Simulations ◽  
Vapor Deposition ◽  
Density Functional ◽  
Chemical Vapor ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Dynamics Simulations

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the...

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...

Cluster, Surface and Bulk Properties of ZnCd Binary Alloys: Molecular-Dynamics Simulations

2005 ◽  
Vol 502 ◽  
pp. 51-56 ◽  
Author(s):  
Sakir Erkoc
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Structural Features ◽  
Bulk Materials ◽  
Bulk Properties ◽  
Atom Clusters ◽  
Dynamics Simulations ◽  
Mixed Clusters ◽  
Stable Structures

The structural and electronic properties of isolated neutral ZnmCdn clusters for m+n £ 3 have been investigated by performing density functional theory calculations at B3LYP level. The optimum geometries, vibrational frequencies, electronic structures, and the possible dissosiation channels of the clusters considered have been obtained. An empirical many-body potential energy function (PEF), which comprices two- and three-body atomic interactions, has been developed to investigate the structural features and energetics of ZnmCdn (m+n=3,4) microclusters. The most stable structures were found to be triangular for the three-atom clusters and tetrahedral for the four-atom clusters. On the other hand, the structural features and energetics of Znn-mCdm (n=7,8) microclusters, and Zn50, Cd50, Zn25Cd25, Zn12Cd38, and Zn38Cd12 nanoparticles have been investigated by performing molecular-dynamics computer simulations using the developed PEF. The most stable structures were found to be compact and three-dimensional for all elemental and mixed clusters. An interesting structural feature of the mixed clusters is that Zn and Cd atoms do not mix in mixed clusters, they come together almost without mixing. Surface and bulk properties of Zn, Cd, and ZnCd systems have been investigated too by performing molecular-dynamics simulations using the developed PEF. Surface reconstruction and multilayer relaxation on clean surfaces, adatom on surface, substitutional atom on surface and bulk materials, and vacancy on surface and bulk materials have been studied extensively.

Density-functional-based molecular-dynamics simulations of molten salts

2005 ◽  
Vol 123 (13) ◽  
pp. 134510 ◽  
Author(s):  
Sandrine Hazebroucq ◽  
Gérard S. Picard ◽  
Carlo Adamo ◽  
Thomas Heine ◽  
Sibylle Gemming ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Molten Salts ◽  
Density Functional ◽  
Dynamics Simulations

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.

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