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We performed molecular dynamics simulations of coalescence of two vacancies in a tungsten (W) crystal to elucidate the effect of temperature and hydrogen atoms. Simulations were performed for two types of vacancy structures, $\mathrm{V}_9 +…

Materials Science · Physics 2024-07-03 Sotaro Tsuru , Hiroaki Nakamura , Yuki Goto , Miyuki Yajima , Seiki Saito , Shunsuke Usami

We study the kinetics of the redistribution of impurity atoms in the elastic fields of dislocations by computer simulation methods. A work consists of several stages. The first is the simulation of a dislocation core structure with a…

Materials Science · Physics 2021-01-05 A. A. Gusev , A. V. Nazarov

Vacancy mechanism plays a dominant role in the atomic migration when a close-packed disordered alloy undergoes ordering transition. However, the calculation of thermal vacancy formation energies (VFEs) of random solid solutions is usually…

Materials Science · Physics 2017-02-13 H. B. Luo , Q. M. Hu , J. Du , A. R. Yan , J. P. Liu

A comprehensive, critical study of the vibrational, thermodynamic and thermoelastic properties of bcc iron is presented, using well established semi-empirical embedded-atom method potentials available in the literature. Classical molecular…

Materials Science · Physics 2018-05-18 Daniele Dragoni , Davide Ceresoli , Nicola Marzari

We consider a problem of description of quantum correlations and dispersions of subsystems of complex open systems. Based on our previous results we proposed a method to evaluate pure quantum contributions from total statistical…

Quantum Physics · Physics 2016-01-26 Illarion Dorofeyev

We present a thermodynamic theory of the Kovacs effect based on the idea that the configurational degrees of freedom of a glass-forming material are driven out of equilibrium with the heat bath by irreversible thermal contraction and…

Materials Science · Physics 2016-12-14 Eran Bouchbinder , J. S. Langer

We describe a numerical scheme for exactly simulating the heat current behavior in a quantum harmonic chain with self-consistent reservoirs. Numerically-exact results are compared to classical simulations and to the quantum behavior under…

Mesoscale and Nanoscale Physics · Physics 2015-05-28 Malay Bandyopadhyay , Dvira Segal

We propose an approach to calculate the anharmonic part of the volumetric-strain and temperature dependent free energy of a crystal. The method strikes an effective balance between accuracy and computational efficiency, showing a $\times10$…

Materials Science · Physics 2019-07-17 Thomas A. Mellan , Andrew I. Duff , Blazej Grabowski , Michael W. Finnis

An atom, coupled linearly to an environment, is considered in a harmonic approximation in thermal equilibrium inside a cavity. The environment is modeled by an infinite set of harmonic oscillators. We employ the notion of dressed states to…

Quantum Physics · Physics 2012-01-25 F. C. Khanna , A. P. C. Malbouisson , J. M. C. Malbouisson , A. E. Santana

Melting behaviors of defective crystals under extreme conditions are theoretically investigated using the statistical moment method. In our theoretical model, heating processes cause missing atoms or vacancies in crystal structures via…

Materials Science · Physics 2020-05-15 Tran Dinh Cuong , Anh D. Phan

We use a physically-based crystal plasticity model to predict the yield strength of body-centered cubic (bcc) tungsten single crystals subjected to uniaxial loading. Our model captures the thermally-activated character of screw dislocation…

Materials Science · Physics 2015-12-22 David Cereceda , Martin Diehl , Franz Roters , Dierk Raabe , J. Manuel Perlado , Jaime Marian

We study transient thermal processes in infinite harmonic crystals with complex (polyatomic) lattice. Initially particles have zero displacements and random velocities such that distribution of temperature is spatially uniform. Initial…

Statistical Mechanics · Physics 2019-06-24 Vitaly A. Kuzkin

We present molecular dynamics simulations of the homogeneous (mechanical) melting transition of a bcc metal, vanadium. We study both the nominally perfect crystal as well as one that includes point defects. According to the Born criterion,…

Materials Science · Physics 2009-11-10 V. Sorkin , E. Polturak , Joan Adler

The first-principles calculation of contributions of phonon and electron excitations to free formation, binding, and migration energies of defects is illustrated in the case of bcc-Fe. First of all, the ground state properties of the…

Materials Science · Physics 2015-08-11 D. Murali , M. Posselt , M. Schiwarth

We simulate the dislocation core structure in bcc iron using the modified Molecular Static method. A feature of this method is the application of an iterative procedure in which the atomic structure in the vicinity of the defect and the…

Materials Science · Physics 2021-01-05 A. A. Gusev , A. V. Nazarov

We present a systematic methodology for the accurate calculation of defect structures in supercells which we illustrate with a study of the neutral vacancy in silicon. This is a prototypical defect which has been studied extensively using…

Materials Science · Physics 2009-11-10 M. I. J. Probert , M. C. Payne

Icosahedral quasicrystals spontaneously form from the melt in simulations of Al--Cu--Fe alloys. We model the interatomic interactions using oscillating pair potentials tuned to the specific alloy system based on a database of density…

Materials Science · Physics 2020-03-04 Marek Mihalkovic , Michael Widom

Despite the widespread use of silicon in modern technology, its peculiar thermal expansion is not well-understood. Adapting harmonic phonons to the specific volume at temperature, the quasiharmonic approximation, has become accepted for…

This paper suggests using the configurational temperature $\Tc$ for quantifying how far an active-matter system is from thermal equilibrium. We measure this ``distance'' by the ratio of the systemic temperature $\Ts$ to $\Tc$, where $\Ts$…

Soft Condensed Matter · Physics 2023-02-20 Shibu Saw , Lorenzo Costigliola , Jeppe C. Dyre

In a large variety of ideal crystals we found that when rapidly migrating atoms squash or annihilate a neighbouring vacancy and produce a disordered cluster, the heat of migration stored in the system exceeds the enthalpy increase required…

Materials Science · Physics 2015-05-19 L. W. Wang , Q. Wang , K. Q. Lu