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Atomic-Scale Simulation of Tribological and Related Phenomena
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Judith A. Harrison, Steven J. Stuart, Donald W. Brenner
Molecular dynamics simulations involve tracking the motion of atoms and molecules as a function of time. Typically, this motion is calculated by the numerical solution of a set of coupled differential equations (Gear, 1971; Heermann, 1986; Allen and Tildesley, 1987). For example, Newton’s equation of motion, F=ma=mdvdt, where F is the force on a particle, m is its mass, a its acceleration, v its velocity, and t is time, yield a set of 3n (where n is the number of particles) second-order differential equations that govern the dynamics. These can be solved with finite-time-step integration methods, where time steps are on the order of 1/25 of a vibrational frequency (typically tenths to a few femtoseconds) (Gear, 1971). Most current simulations then integrate for a total time of picoseconds to nanoseconds. The evaluation of these equations (or any of the other forms of classical equations of motion) requires a method for obtaining the force F between atoms.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Molecular dynamics is a simulation procedure consisting of the computation of the motion of atoms in a molecule or of individual atoms or molecules in solids, liquids and gases, according to Newton’s laws of motion. The forces acting on the atoms, required to simulate their motions, are generally calculated using molecular mechanics force fields.
Physical and Mathematical Models for Nanosystems Simulation
Published in Alexander V. Vakhrushev, Computational Multiscale Modeling of Multiphase Nanosystems, 2017
It should be noted that the above-discussed calculation methods are not isolated. For the solution of a number of problems they can be used simultaneously. For example, the calculation of the trajectories of the motion of atoms and molecules can be carried out by the molecular dynamics methods, while the forces of the interaction between the atoms and molecules at each calculation step in time can be calculated by the quantum mechanics methods. The motion of nanoparticles in the gas phase can be considered as the motion of super molecules, the trajectory of which is calculated by the mesodynamics methods, and the motion of atoms and molecules of the gas mixture—with the use of the molecular dynamics methods.
Research on mechanism of ultrasonic-assisted nano-cutting of sapphire based on molecular dynamics
Published in Mechanics of Advanced Materials and Structures, 2023
Fei Zhou, Jinkai Xu, Wanfei Ren, Peng Yu, Huadong Yu
Molecular dynamics simulation is a method to study the evolution in time of a material model consisting of discrete atoms, which takes samples from different systems of states composed of particles in order to calculate the conformational integral of the system. The trajectories of the atoms are determined by numerically solving newton's equations of motion, so that the whole system follows Newton's second law during the simulation. The process of molecular dynamics simulation is based on the input of atomic information and initial conditions, the calculation of the force acting on the atom, and the calculation of the new position, velocity and acceleration of each atom in the atomic system over time based on Newton's second law. Where the force is the result of the derivative of the potential function the interatomic interaction potential function characterizes the interaction between the atoms and is the basis for the entire kinetic process.
Transverse wave propagation analysis in single-walled and double-walled carbon nanotubes via higher-order doublet mechanics theory
Published in Waves in Random and Complex Media, 2023
After the invention of CNTs [1], they are used in a wide range of applications in the design of atomic force microscope, nano-fillers for composite materials, nano-scale electronic devices, nano-actuators and nano-motors due to their superior mechanical, electrical and physical properties [2]. In order to investigate the mechanical performance of CNTs, atomistic modeling such as molecular dynamics simulation has been used [3,4]. Molecular dynamics simulation is applicable for systems with a small number of molecules and atoms, whereas it is restrained for large-scale systems. Fortunately, continuum theories can be used effectively for mechanical analysis of CNTs which have high aspect ratios such as nanobeams and nanorods. Mostly used continuum theories in mechanical analysis of scale-dependent structures can be regarded as couple stress model [5,6], nonlocal stress gradient theory [7,8] and strain gradient theory [9]. Unlike the classical elasticity theory, these continuum theories include the size effect in static and dynamic analyses of the micro/nanostructures.
Adsorption behaviour of NaCl solution on the surface of MgO: a molecular dynamics study
Published in Molecular Physics, 2019
Xiaoli Tang, Qingfei Bian, Qiuwang Wang, Min Zeng
Molecular dynamics simulation is based on the Newton’s law of motion, which starts from a set of molecules occupying a region of space, with each atom assigned a random velocity corresponding to the Boltzmann distribution at the temperature of interest. Force field is used to solve the motion of the mass particle, whose parameters are obtained by quantum mechanical calculation or experimental method. According to the Born–Oppenheimer approximation principle, the motion of electrons is neglected, and the energy of the system is regarded as a function of the position of the nucleus. In this study, the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) [25] is used to run this simulation and the details are as follows.