Papers by Vladimir Stegailov
Modelling and Simulation in Materials Science and Engineering, 2013
A new interatomic potential for a uranium-molybdenum system with xenon is developed in the framew... more A new interatomic potential for a uranium-molybdenum system with xenon is developed in the framework of an embedded atom model using a forcematching technique and a dataset of ab initio atomic forces. The verification of the potential proves that it is suitable for the investigation of various compounds existing in the system as well as for simulation of pure elements: U, Mo and Xe. Computed lattice constants, thermal expansion coefficients, elastic properties and melting temperatures of U, Mo and Xe are consistent with the experimentally measured values. The energies of the point defect formation in pure U and Mo are proved to be comparable to the density-functional theory calculations. We compare this new U-Mo-Xe potential with the previously developed U and Mo-Xe potentials. A comparative study between the different potential functions is provided. The key purpose of the new model is to study the atomistic processes of defect evolution taking place in the U-Mo nuclear fuel. Here we use the potential to simulate bcc alloys containing 10 wt% of intermetallic Mo and U 2 Mo.
Microscopic mechanisms and kinetics of dynamic fracture of crystalline materials are analyzed. Th... more Microscopic mechanisms and kinetics of dynamic fracture of crystalline materials are analyzed. The work is based on the molecular dynamics modeling and simulation within the embedded atom method model for interatomic interactions in metals. An attempt is made to present the results of molecular dynamics calculations as kinetic constitutive relations for the description of the elementary processes of fracture. The kinetics of melting, rates of nucleation and growth of voids are evaluated separately for a range of pressures and temperatures. The influence of the material microstructure (grain boundaries, dislocation subsystem, nanosize pores and inclusions) on failure mechanisms is studied. An effect of melting in rarefaction waves on the fracture kinetics and the spall strength of monocrystalline and polycrystalline metals is discussed. A comparison with the shock wave experimental data on the spall strength is presented.
Bulletin of the American …, 2009
Fracture kinetic model of liquids based on molecular dynamics simulations is presented. Stretched... more Fracture kinetic model of liquids based on molecular dynamics simulations is presented. Stretched liquid appears as a result of large energy deposition to condensed matter, for example, under laser processing or shock-wave loading of materials. The kinetic model of fracture includes two processes: nucleation and growth of voids (NAG approach). The rates of nucleation and growth of voids are evaluated separately from molecular dynamics simulations on the example of Lennard-Jones liquid. Pressure and temperature dependences of nucleation rate can be approximated in the form of classical nucleation theory. The kinetics of void growth is shown to satisfy the hydrodynamic Rayleigh-Plesset equation. The fracture kinetics and spall strength are determined by means of the proposed model. The results of calculations show good agreement with the experimental data. This work was supported by the RAS programs # 11, 12, and SNL under the US DOE/NNSA ASC program.
Physical Review B, 2011
The formation of defects in bcc Mo lattice as a result of 50-keV Xe bombardment is studied via at... more The formation of defects in bcc Mo lattice as a result of 50-keV Xe bombardment is studied via atomistic simulation with an interatomic potential developed using the force-matching ab initio based approach. The defect evolution in the cascade is described. Diffusion and interaction of interstitials and vacancies are analyzed. Only small interstitial atom clusters form directly in the cascade. Larger clusters grow only via aggregation at temperatures up to 2000 K. Stable forms of clusters demonstrate one-dimensional diffusion with a very high diffusion coefficient and escape quickly to the open surface. Point vacancies have much lower diffusivity and do not aggregate. The possibility of a large prismatic vacancy loop formation near the impact surface as a result of fast recrystallization is revealed. The mobility of the vacancy dislocation loop segments is high, however, the motion of the entire loops is strongly hindered by neighbor point defects. This paper explains the existence of the large prismatic vacancy loops and the absence of the interstitial loops in the recent experiments with ion irradiation of Mo foils.
International Journal of …, 2010
Microscopic mechanisms and kinetics of dynamic fracture of crystalline materials are analyzed. Th... more Microscopic mechanisms and kinetics of dynamic fracture of crystalline materials are analyzed. The work is based on the molecular dynamics modeling and simulation within the embedded atom method model for interatomic interactions in metals. An attempt is made to present the results of molecular dynamics calculations as kinetic constitutive relations for the description of the elementary processes of fracture. The kinetics of melting, rates of nucleation and growth of voids are evaluated separately for a range of pressures and temperatures. The influence of the material microstructure (grain boundaries, dislocation subsystem, nanosize pores and inclusions) on failure mechanisms is studied. An effect of melting in rarefaction waves on the fracture kinetics and the spall strength of monocrystalline and polycrystalline metals is discussed. A comparison with the shock wave experimental data on the spall strength is presented.
APS Meeting Abstracts, 2002
Molecular dynamics method is used for the study of homogeneous nucleation in superheated model cr... more Molecular dynamics method is used for the study of homogeneous nucleation in superheated model crystal. Fcc-lattice of N particles interacting via U=ɛ(σ/r)^n potential is simulated with periodic boundary conditions. In this case system properties depend only on a single parameter X ˜ ρσ^3(ɛ/k_BT)^3/n, where ρ - density, T - temperature. This potential was used for simulation of liquid and solid metals, high pressure range included [1]. The simulation peculiarities connected with Lyapunov instability and dynamical memory time are discussed. The lifetime τ of a metastable state is limited. Ensemble of statistically independent MD-runs allows us to calculate τ distribution and find the most probable lifetime τ for the fixed superheating value. The τ^* value is inversely proportional to the MD cell volume V (or proportional to N). The homogeneous nucleation rate J=(Vτ^*)-1 is the value, which is independent of V and N. Our simulation results can be fitted to J=J_0exp(-W/k_BT), where W=cρ^n/3 is the energy of the critical nucleus formation. The values of c and J0 are calculated for several n. Estimation of the maximum nucleation rate J_max allows us to obtain the corresponding kinetic limit [2] (X-1)_max of crystal stability for given n. The work is supported by RFBR (00-02-16310a, 02-02-06654mas) and Integratsiya (U0022). [1] W.G. Hoover et al. J. Chem Phys. 63 (1975) 5434. [2] B. Rethfeld et al. PR 65B (2002) 092103.
Computer Physics Communications, 2007
Melting front velocity dependencies on temperature are calculated using the molecular-dynamics me... more Melting front velocity dependencies on temperature are calculated using the molecular-dynamics method for the EAM models of Al and Fe as well as for the Lennard-Jones system. Different surface orientations are considered. It is shown that the Broughton-Gilmer-Jackson theory of the collision-limited growth can describe the results obtained. The isochoric bulk solid melting and decay under ultrafast heating is simulated for mono-and polycrystalline models.
Molecular Simulation, 2005
An attempt is made to formulate a set of requirements for simulation and modelling of relaxation ... more An attempt is made to formulate a set of requirements for simulation and modelling of relaxation in dense media. Each requirement is illustrated by examples of numerical simulation of particles with different types of interaction given by softsphere, Lennard -Jones, embedded atom method or Coulomb potential. The approaches developed are expected to be universal for some classes of relaxation processes in liquids, fluids, crystals and plasmas.
Computer physics communications, 2002
The concept of dynamical memory time t m is discussed. The relation between t m , fluctuation of ... more The concept of dynamical memory time t m is discussed. The relation between t m , fluctuation of energy E and K-entropy (Lyapunov exponent) is treated. The meaning of t m for real systems is related to the thermal and Langevin noise and quantum uncertainty. Relaxation of kinetic energy to equilibrium state was studied by MDM for non-equilibrium strongly coupled plasmas. Violation of the microscopic reversibility principle in some enzymatic reactions is discussed.
Molecular Simulation, 2004
ABSTRACT
Journal of Molecular Liquids, 2006
The performance of neighbor list techniques in molecular dynamics simulations depends on a variet... more The performance of neighbor list techniques in molecular dynamics simulations depends on a variety of parameters, which may be adjusted for maximum efficiency. Here, a model is presented which allows to choose optimal parameters for the performance of Verlet-and linked-cell lists. In several cases, an efficiency gain of å 50% is found if parameters are chosen adequately. Test cases are presented for Lennard -Jones systems at different state points. Good agreement between analytical model and simulation results is found. D
Uploads
Papers by Vladimir Stegailov