Searcharxiv⌕ Search

arXiv subjects

Yu. D. Fomin

Publications and source records attributed to Yu. D. Fomin.

At least 19 recordsLinked to original sources
arXiv2026

Voids in liquids: peculiarities of molecular dynamics simulation of fluid systems

Molecular dynamics is a powerful tool to investigate the properties of fluid systems. However, a correct interpretation of the results of simulations is required. In particular, some simulations show appearance of large voids in liquids, which contradicts our common sense on what is liquid. In the present paper we discuss the origin of large cavities liquids in molecular dynamics simulations. We demonstrate that the cavities appear either if the temperature of the system is above the critical temperature of liquid-gas transition or if the system is in two-phase liquid-gas region. These conclusions are illustrated by several examples from literature and our own simulations.

cond-mat.soft↗
arXiv2026

Melting of thin silicon films: a molecular dynamics study with two machine learning potentials

Thermal stability of silicene and thin silicon films is studied by molecular dynamics using two machine-learning potentials, SNAP and GAP. For SNAP potential, systems ranging from a single silicene layer to films of 36 layers are considered. Silicene is found to lose its structure at 500 K. The decomposition temperature increases with film thikness and reaches saturation at about 28 layers, corresponding to the bulk melting point of the SNAP model (1380 K). Thin films up to 8 layers exibit two-phase coexistence upon decomposition, while thicker films undergo surface melting followed by complete collapse into the liquid state. The GAP potential, although more accurate for bulk silicon, fails to describe the gas phase: silicene modelled with GAP decomposes into a set of small clusters. The results are compared with earlier data for the Stillinger-Weber potential.

cond-mat.mtrl-sci↗
arXiv2025

Melting line of silicon modelled with a machine-learning potential

In the present study we investigate the phase diagram of silicon within the framework of SNAP machine learning potential model. We show that the melting line of diamond phase of silicon is a linear function of pressure, which is in good agreement with experimental data. At the same time the melting temperature is strongly underestimated. Also, this model fails to predict the high pressure phases of silicon.

cond-mat.soft↗
arXiv2024

Collective excitations in liquid carbon tetrachloride: a molecular dynamics study

We perform a molecular dynamic study of collective excitations of carbon tetrachloride and compare the results with experimental data from the literature. The data of simulations are in good argeement with the experimental ones. The results of the simulations confirm the presence of large positive sound dispersion (PSD) in carbon tetrachloride, which should be related to some relaxation processes which do not take place in atomic systems.

cond-mat.soft↗
arXiv2024

Kob-Andersen model crystal structure: genetic algorithms vs spontaneous crystallization

For the first time, the crystal structure of the Kob-Andersen mixture has been probed by genetic algorithms calculations. The stable structures of the system with different molar fractions of the components have been identified and their stability at finite temperature has been verified. A possibility to obtain these structures by spontaneous crystallization of a liquid has been checked.

cond-mat.soft↗
arXiv2024

A rare gas mixture: From rigid to gas-like fluid by a mutual concentration change

For a number of mixtures of rate gases at high pressures, sound speed minima are experimentally observed depending on the concentration. This behavior has not yet been explained. We have studied the behavior of a mixture of argon and helium using computer simulation. Sound speed minima have been discovered at a certain concentration, which is in good agreement with experimental data. It is shown that this behavior is due to the fact that the P and T parameters for gas mixtures are near the Frenkel line, separating the states of "rigid" and quasi-gas fluid.

cond-mat.soft↗
arXiv2023

The influence of Gaussian pinning on the melting scenario of a two-dimensional soft-disk system: First-Order versus Continuous Transition

Two-dimensional systems are realized experimentally as thin layers on a substrate. The substrate can have some imperfections (defects of the crystalline structure, chemical impurities, etc.), which demonstrate stronger interaction with the particles of the two-dimensional layer than the rest of the system. Such randomly distributed centers of strong interactions are called "pinning centers". The presence of random pinning can substantially change the behavior of the system. It not only shifts the melting point of the system, but can also change the melting scenario itself. In the present paper the influence of Gaussian pinning on the melting scenario of a two-dimensional system of soft disks is studied by means of molecular dynamics simulation. We randomly introduce into the system of soft disks a set of "pinning centers" which attract the particles via the Gauss potential. We observe that increasing the depth of a Gaussian well leads to a change in the melting scenario of the system. The results demonstrate that simple kind of quenched disorder can significantly affect the melting scenario of two-dimensional systems, offering the possibility of its introduction in complex experiments and studying its influence on the self-assembly and phase diagram of two-dimensional systems in rotating external fields.

cond-mat.soft↗
arXiv2023

Sublimation of silicene and thin silicon films: a view from molecular dynamics simulation

A molecular dynamics simulation of sublimation of silicene and silicon films of different thikness is performed. It is shown that thiner films sublimate at lower temperatures. The sublimation temperature comes to a saturated value of $T=1725$ K at the films thiker than $16$ atomc layers. These results are consistent with the surface mediated collaps of the crystal structure. At the same time this mechanism is different from the crystal structure collapse of graphite and graphene.

cond-mat.mtrl-sci↗
arXiv2022

Molecular simulation of bulk and confined (1,1,1,3,3-pentafluorobutane)

Here we present a computational study of the thermodynamic and structural properties of bulk and confined (1,1,1,3,3-pentafuorobutane) with different lengths of the carbon backbone. The DREIDING force field model has been used in the method of molecular dynamics. In order to study the effect of confinement we have placed (1,1,1,3,3-pentauorobutane) molecules between two graphene walls. In order to study the influence of pore loading on system behavior we have simulated systems of the same size, but with a different number of (1,1,1,3,3-pentauorobutane) molecules, from 200 to 2000. The equations of state at $T = 300$ K in a wide range of densities for all considered systems had a single peculiarity that is attributed to gas-liquid transition. From the two-dimensional radial distribution functions, density profile and angular distribution we have observed the systems split into layers with amorphization rather than crystallization in them.

cond-mat.soft↗
arXiv2022

Ultrasonic study and molecular simulation of propylene glycol at pressure up to 1.4 GPa

We report an ulsrasonic measurements of density and bulk modulus of propylene glycol at room temperature and at the temperature of liquid nitrogen combined with molecular dynamics simulations with two different force fields. We find that experimental density of propylene glycol at room temperature is well described within COMPASS force fields simulations, while the bulk modulus from simulation deviates from the experimental one. Number of hydrogen bonds in propylene glycol is also evaluated.

cond-mat.soft↗
arXiv2022

First-principles molecular dynamics simulation of liquid indium

We report an ab-initio simulation of liquid Indium in a wide range of pressures and temperatures. We calculate equation of state, thermal expansion and compressibility coefficients. The structure of the system is analyzed by radial distribution functions and structure factors. The results are compared with available experimental data.

cond-mat.soft↗
arXiv2021

Anomalous behavior of two-dimensional Hertzian sphere system

The anomalous behavior of a two-dimensional system of Hertzian spheres with exponent $α= 7/2 $ has been studied using the method of molecular dynamics. The phase diagram of this system is the melting line of a triangular crystal with several maxima and minima. Water-like density and diffusion anomalies have been found in the reentrant melting regions. Noteworthy, a density anomaly has been observed not only in the liquid and hexatic but also solid phase. The calculations of the phonon spectra of longitudinal and transverse modes have yielded negative dependence of the frequency of transverse modes on density along all directions in the regions with a density anomaly. This indicates an association of the density anomaly with transverse oscillations of the crystal lattice. The regions of density and diffusion anomalies have been drawn on the phase diagram. It has been found that the stability regions of anomalous diffusion extend to temperatures well above maximum melting point $T = 0.0058$ of the triangular crystal. From analysis of the translational order parameter, which decreases with increasing density in the reentrant melting regions, the presence of a structural anomaly in the system has been assumed.

cond-mat.soft↗
arXiv2021

Glass transition in monatomic systems: smearing of the same structure vs two structure competition

In the present paper we discuss the properties of Voronoi polygons in several monatomic glass-forming systems and compare them with those of the Kob-Andersen mixture. We show that two mechanisms of glass formation are possible: smearing of Voronoi polygons or formation of polygons of two different shapes. Both mechanisms lead to disturbance of the crystalline order in the system and glass transition.

cond-mat.soft↗
arXiv2021

A new mechanism of structural transition in 2D Hertzian spheres in the presence of random pinning

Using molecular dynamics simulation we have investigated the influence of random pinning on the phase diagram and melting scenarios of a two-dimensional (2D) system with the Hertz potential for $α=5/2$. For the first time it has been shown that random pinning can cardinally change the mechanism of first-order transition between the different crystalline phases (triangular and square) by virtue of generating hexatic and tetratic phases: a triangular crystal to hexatic transition is of the continuous Berezinskii-Kosterlitz-Thouless (BKT) type, a hexatic to tetratic transition is of the first-order, and finally, a continuous BKT type transition from tetratic to the square crystal.

cond-mat.soft↗
arXiv2020

Crystal structures of a core-softened system confined in a narrow slit pore

We investigate a behavior of a core-softened system in a thin slit pore (the width of the pore is equil to three diameters of the particles). In previous studies it was shown that strongly confined systems form crystalline phases which consist of several triangular or square layers. These phases can be also considered as cuts of FCC or HCP structures. We show that the behavior of the core-softened system is more complex. We observe also a quasicrystalline phase. Moreover, the phase with two triangular layers appears at lower densities than the one with two square layers which is in contrast to the behavior of the systems studied before. These results demonstrate that the phase behavior of strongly confined systems can be even more complex than it was supposed before.

cond-mat.soft↗
arXiv2020

Phase diagram of a two-dimensional system which stabilizes Kagome lattice

Phase diagram of a two-dimensional system with a potential which stabilizes Kagome lattice is calculated. It is shown that this system demonstrate a set of crystalline and the regions of stability of these phases are calculated. The scenarios of melting of triangular and square crystals of the system are determined.

cond-mat.soft↗
arXiv2020

Melting line and thermodynamic properties of a supeionic compound SrCl$_2$ by molecular dynamics simulation

In the present paper we study the thermodynamic properties of superionic conductor $SrCl_2$ at high temperatures by means of molecular dynamics method. Firstly, we calculate the melting line. Then we compute the equations of state and the response functions (heat capacity, thermal expansion coefficient, etc) at the temperatures up to the melting. We show that the response functions show maxima or minima at the temperatures well above the temperature of transition into the conductive state, and therefore are not related to this transition.

cond-mat.soft↗