Atomistic Simulation of Vapor-Phase Nanoparticle Formation

1994 ◽  
Vol 351 ◽  
Author(s):  
Michael R. Zachariah ◽  
Michael J. Carrier ◽  
Estela Blaisten-Barojas
Keyword(s):  
Atomistic Simulation ◽  
Equations Of Motion ◽  
Stable State ◽  
Dynamic Effects ◽  
Diffusion Constants ◽  
Large Heat ◽  
Dynamics Simulations ◽  
Three Body ◽  
The Impact ◽  
Weber Potential

ABSTRACTIn order to understand from a fundamental view how nanoparticles form and grow, classical molecular dynamics simulations of cluster growth and energy accommodation processes have been conducted for clusters of silicon (< 1000 atoms), over a wide temperature range. Simulations involved solution of the classical equations of motion constrained with the three body Stillinger-Weber potential. The results show the large heat release and resulting cluster heating during a cluster-cluster collision event, and the corresponding time evolution of the internal energy to a more stable state. Dynamic effects associated with the temperature of the cluster and the impact parameter are also clearly evident. In particular, clusters show a large sensitivity to temperature in the rate of coalescence, particularly at low temperature. Calculated diffusion coefficients are significantly larger than surface diffusion constants stated in the literature. Phonon density of states spectra do not seem to show size effects.

Multi-Million Atom Molecular-Dynamics Simulations of Stresses in Si(111)/Si3N4 Nanopixels

1999 ◽  
Vol 592 ◽  
Author(s):  
Martina E. Bachlechner ◽  
Andrey Omeltchenko ◽  
Phillip Walsh ◽  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Molecular Dynamics Simulations ◽  
Electronic Structure Calculations ◽  
Parallel Computers ◽  
Dynamics Simulations ◽  
Three Body ◽  
Stress Domains ◽  
Structure Calculations ◽  
Weber Potential

ABSTRACTThe stress distribution in Si(111)/Si3N4(0001) and Si(111)/a-Si3N4 nanopixels are studied using molecular dynamics simulations on parallel computers. Bulk Si is described by the Stillinger-Weber potential and Si3N4 is represented by a combination of two- and three-body interactions that include steric, charge transfer, polarizability and covalent forces. The charge transfer at the interface is extracted from self-consistent electronic structure calculations. The molecular dynamics simulations for Si(111)/a-Si3N4 nanopixels involve two pixel sizes: 25nm and 54 nm (the systems consist of 3.7 million and 10 million atoms, respectively). In both systems we find stress domains at the interface, which extend into the silicon substrate. The nature of the stress domains is discussed.

scholarly journals A Study of Single- and Double-Averaged Second-Order Models to Evaluate Third-Body Perturbation Considering Elliptic Orbits for the Perturbing Body

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
R. C. Domingos ◽  
A. F. Bertachini de Almeida Prado ◽  
R. Vilhena de Moraes
Keyword(s):  
Body Problem ◽  
Equations Of Motion ◽  
Second Order ◽  
Restricted Three Body Problem ◽  
Three Body Problem ◽  
Third Body ◽  
Elliptic Orbits ◽  
Three Body ◽  
The Impact ◽  
Third Body Perturbation

The equations for the variations of the Keplerian elements of the orbit of a spacecraft perturbed by a third body are developed using a single average over the motion of the spacecraft, considering an elliptic orbit for the disturbing body. A comparison is made between this approach and the more used double averaged technique, as well as with the full elliptic restricted three-body problem. The disturbing function is expanded in Legendre polynomials up to the second order in both cases. The equations of motion are obtained from the planetary equations, and several numerical simulations are made to show the evolution of the orbit of the spacecraft. Some characteristics known from the circular perturbing body are studied: circular, elliptic equatorial, and frozen orbits. Different initial eccentricities for the perturbed body are considered, since the effect of this variable is one of the goals of the present study. The results show the impact of this parameter as well as the differences between both models compared to the full elliptic restricted three-body problem. Regions below, near, and above the critical angle of the third-body perturbation are considered, as well as different altitudes for the orbit of the spacecraft.

Atomistic simulation of the uniaxial compression of black phosphorene nanotubes

2018 ◽  
Author(s):  
Van-Trang Nguyen ◽  
Minh-Quy Le
Keyword(s):  
Finite Element Method ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Uniaxial Compression ◽  
Critical Stress ◽  
Atomistic Simulation ◽  
Critical Strain ◽  
Bond Breaking ◽  
Black Phosphorene ◽  
Weber Potential

We study through molecular dynamics finite element method with Stillinger-Weber potential the uniaxial compression of (0, 24) armchair and (31, 0) zigzag black phosphorene nanotubes with approximately equal diameters. Young's modulus, critical stress and critical strain are estimated with various tube lengths. It is found that under uniaxial compression the (0, 24) armchair black phosphorene nanotube buckles, whereas the failure of the (31, 0) zigzag one is caused by local bond breaking near the boundary.

Molecular Dynamics Study Of Si/Si3N4 Interface

1996 ◽  
Vol 446 ◽  
Author(s):  
Martina E. Bachlechner ◽  
Ingvar Ebbsjö ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Charge Transfer ◽  
Md Simulations ◽  
Electronic Structure Calculations ◽  
Interface Structure ◽  
Bond Bending ◽  
Three Body ◽  
Structure Calculations ◽  
Weber Potential

AbstractStructural correlations at the Si(111)/Si3N4(0001) interface are studied using the molecular dynamics (MD) method. In the bulk, Si is described by the Stillinger-Weber potential and Si3N4 by an interaction potential which contains two-body (steric, Coulomb, electronic polarizabilities) and three-body (bond bending and stretching) terms. At the interface, the charge transfer from silicon to nitrogen is taken from LCAO electronic structure calculations. Using these Si, Si3N4 and interface interactions in MD simulations, the interface structure (atomic positions, bond lengths, and bond angles) is determined. Results for fracture in silicon are also presented.

Molecular Dynamics Study of Ion Impact Phenomena and Compressive Stress in Thin Films

1993 ◽  
Vol 317 ◽  
Author(s):  
N.A. Marks ◽  
P. Guan ◽  
D.R. Mckenzie ◽  
B.A. PailThorpe
Keyword(s):  
Molecular Dynamics ◽  
Three Dimensional ◽  
Carbon Films ◽  
Loss Mechanism ◽  
Ion Energy ◽  
Lennard Jones ◽  
Impact Phenomena ◽  
Ion Impact ◽  
Dynamics Simulations ◽  
The Impact

ABSTRACTMolecular dynamics simulations of nickel and carbon have been used to study the phenomena due to ion impact. The nickel and carbon interactions were described using the Lennard-Jones and Stillinger-Weber potentials respectively. The phenomena occurring after the impact of 100 e V to 1 keV ions were studied in the nickel simulations, which were both two and three-dimensional. Supersonic focussed collision sequences (or focusons) were observed, and associated with these focusons were unexpected sonic bow waves, which were a major energy loss mechanism for the focuson. A number of 2D carbon films were grown and the stress in the films as a function of incident ion energy was Measured. With increasing energy the stress changed from tensile to compressive and reached a maximum around 50 eV, in agreement with experiment.

Dynamic effects in the impact testing of brittle materials

1975 ◽  
Vol 10 (4) ◽  
pp. 621-632 ◽  
Author(s):  
P. W. McMillan ◽  
J. R. Tesh
Keyword(s):  
Brittle Materials ◽  
Impact Testing ◽  
Dynamic Effects ◽  
The Impact

scholarly journals Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Hiroyuki Tajima ◽  
Junichi Takahashi ◽  
Simeon Mistakidis ◽  
Eiji Nakano ◽  
Kei Iida
Keyword(s):  
Spectral Function ◽  
Einstein Condensate ◽  
Three Dimensions ◽  
Quantum Gas ◽  
Many Body ◽  
Bose Einstein Condensate ◽  
Spatial Dimensions ◽  
Three Body ◽  
Bose Einstein ◽  
The Impact

The notion of a polaron, originally introduced in the context of electrons in ionic lattices, helps us to understand how a quantum impurity behaves when being immersed in and interacting with a many-body background. We discuss the impact of the impurities on the medium particles by considering feedback effects from polarons that can be realized in ultracold quantum gas experiments. In particular, we exemplify the modifications of the medium in the presence of either Fermi or Bose polarons. Regarding Fermi polarons we present a corresponding many-body diagrammatic approach operating at finite temperatures and discuss how mediated two- and three-body interactions are implemented within this framework. Utilizing this approach, we analyze the behavior of the spectral function of Fermi polarons at finite temperature by varying impurity-medium interactions as well as spatial dimensions from three to one. Interestingly, we reveal that the spectral function of the medium atoms could be a useful quantity for analyzing the transition/crossover from attractive polarons to molecules in three-dimensions. As for the Bose polaron, we showcase the depletion of the background Bose-Einstein condensate in the vicinity of the impurity atom. Such spatial modulations would be important for future investigations regarding the quantification of interpolaron correlations in Bose polaron problems.

Atomistic Simulation of Volumetric Properties of Epoxy Networks: Effect of Monomer Length

Soft Matter ◽  
2021 ◽  
Author(s):  
Ketan S. Khare ◽  
Cameron F Abrams
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Atomistic Simulation ◽  
Volumetric Properties ◽  
Epoxy Networks ◽  
Design Requirements ◽  
Dynamics Simulations ◽  
Insight Into

Properties of epoxy thermosets can be varied broadly to suit design requirements by altering the chemistry of the component agents. Atomistically-detailed molecular dynamics simulations are well-suited for molecular insight into...

Free vibration analysis and post-critical free vibrations of nanocomposite rotating beams reinforced with graphene platelet

2021 ◽  
pp. 107754632110511
Author(s):  
Arameh Eyvazian ◽  
Chunwei Zhang ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohammad Alkhedher
Keyword(s):  
Natural Frequency ◽  
Thermal Environment ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Free Vibration Analysis ◽  
Beam Theory ◽  
Weight Fraction ◽  
Free Vibrations ◽  
Graphene Platelet ◽  
The Impact

Treatment of the first natural frequency of a rotating nanocomposite beam reinforced with graphene platelet is discussed here. In regard of the Timoshenko beam theory hypothesis, the motion equations are acquired. The effective elasticity modulus of the rotating nanocomposite beam is specified resorting to the Halpin–Tsai micro mechanical model. The Ritz technique is utilized for the sake of discretization of the nonlinear equations of motion. The first natural frequency of the rotating nanocomposite beam prior to the buckling instability and the associated post-critical natural frequency is computed by means of a powerful iteration scheme in reliance on the Newton–Raphson method alongside the iteration strategy. The impact of adding the graphene platelet to a rotating isotropic beam in thermal ambient is discussed in detail. The impression of support conditions, and the weight fraction and the dispersion type of the graphene platelet on the acquired outcomes are studied. It is elucidated that when a beam has not undergone a temperature increment, by reinforcing the beam with graphene platelet, the natural frequency is enhanced. However, when the beam is in a thermal environment, at low-to-medium range of rotational velocity, adding the graphene platelet diminishes the first natural frequency of a rotating O-GPL nanocomposite beam. Depending on the temperature, the post-critical natural frequency of a rotating X-GPL nanocomposite beam may be enhanced or reduced by the growth of the graphene platelet weight fraction.

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