Dynamical properties of hydrogen fluid at high pressures.

The properties of the hydrogen fluid at high pressures are still of interest to the scientific community. The experimentally unreachable dynamical properties could provide new insights into this field. In 2020 [Cheng et al.

The Kob-Andersen model crystal structure: Genetic algorithms vs spontaneous crystallization.

The crystal structure of the Kob-Andersen mixture has been probed by genetic algorithm calculations. The stable structures of the system with different molar fractions of the components have been identified, and their stability at finite temperatures has been verified. It has been found that the structures of composition ABn, where n = 2, 3, or 4, can be formed in the system.

Transfer learning for accurate description of atomic transport in Al-Cu melts.

Machine learning interatomic potentials (MLIPs) provide an optimal balance between accuracy and computational efficiency and allow studying problems that are hardly solvable by traditional methods. For metallic alloys, MLIPs are typically developed based on density functional theory with generalized gradient approximation (GGA) for the exchange-correlation functional. However, recent studies have shown that this standard protocol can be inaccurate for calculating the transport properties or phase diagrams of some metallic alloys.

Local structure, thermodynamics, and melting of boron phosphide at high pressures by deep learning-driven ab initio simulations.

Boron phosphide (BP) is a (super)hard semiconductor constituted of light elements, which is promising for high demand applications at extreme conditions. The behavior of BP at high temperatures and pressures is of special interest but is also poorly understood because both experimental and conventional ab initio methods are restricted to studying refractory covalent materials. The use of machine learning interatomic potentials is a revolutionary trend that gives a unique opportunity for high-temperature study of materials with ab initio accuracy.

Time-dependent exchange creates the time-frustrated state of matter.

Magnetic systems governed by exchange interactions between magnetic moments harbor frustration that leads to ground state degeneracy and results in the new topological state often referred to as a frustrated state of matter (FSM). The frustration in the commonly discussed magnetic systems has a spatial origin. Here we demonstrate that an array of nanomagnets coupled by the real retarded exchange interactions develops a new state of matter, time frustrated matter (TFM).

Structural transformations and thermal stability of RhGe synthesized under high temperature and pressure.

Here, we study B20-type RhGe, a representative of a class of non-centrosymmetric monosilicides and monogermanides, which possess unique topological and magnetic properties important for many possible applications. The stability and phase transitions of the non-equilibrium B20-RhGe phase that can only be obtained under high pressure, are investigated theoretically usingcalculations and experimentally by means of differential scanning calorimetry. For RhGe and, for comparison, for its analogue RhSi, we conducted an evolutionary search for low-energy polymorphic modifications at zero temperature and then performed simulations of their behavior at finite temperatures.

Freezing in two-length-scale systems: complexity, universality and prediction.

Two-length-scale pair potentials arise ubiquitously in condensed matter theory as effective interparticle interactions in molecular, metallic and soft matter systems. The existence of two different bond lengths generated by the shape of potential causes complicated behavior in even one-component systems: polymorphism in solid and liquid states, water-like anomalies, the formation of quasicrystals and high stability against crystallization. Here we address general properties of freezing in one-component two-length-scale systems and argue that solidification of a liquid during cooling is essentially determined by the radial distribution function (RDF) of the liquid.

Structure of the simple harmonic-repulsive system in liquid and glassy states studied by the triple correlation function.

An efficient description of the structures of liquids and, in particular, the structural changes that happen with liquids on supercooling remains to be a challenge. The systems composed of soft particles are especially interesting in this context because they often demonstrate non-trivial local orders that do not allow to introduce the concept of the nearest-neighbor shell. For this reason, the use of some methods, developed for the structure analysis of atomic liquids, is questionable for the soft-particle systems.

Effect of copper concentration on the structure and properties of Al-Cu-Fe and Al-Cu-Ni melts.

We address a relationship between properties of liquid and solid states by comparing structural characteristics and viscosity in Al-Cu-Fe and Al-Cu-Ni melts. The former system forms an equilibrium quasicrystalline phase but the latter does not. We show that the concentration behavior of the viscosity, melting temperature and characteristics of the chemical short-range order correlate with each other.

Anomalous behavior and structure of a liquid of particles interacting through the harmonic-repulsive pair potential near the crystallization transition.

A characteristic property of many soft matter systems is an ultrasoft effective interaction between their structural units. This softness often leads to complex behavior. In particular, ultrasoft systems under pressure demonstrate polymorphism of complex crystal and quasicrystal structures.

Continuous transformation between ferro and antiferro circular structures in [Formula: see text] frustrated Heisenberg model.

Frustrated magnetic compounds, in particular low-dimensional, are topical research due to the persistent uncovering of novel nontrivial quantum states and potential applications. The problem of this field is that many important results are scattered over the localized parameter ranges, while areas in between still contain hidden interesting effects. We consider the [Formula: see text] Heisenberg model on the square lattice and use the spherically symmetric self-consistent approach for spin-spin Green's functions in 'quasielastic' approximation.

Nucleation instability in supercooled Cu-Zr-Al glass-forming liquids.

Few general models representing certain classes of real glass-forming systems play a special role in computer simulations of supercooled liquid and glasses. Recently, it was shown that one of the most widely used model glassformers-the Kob-Andersen binary mixture-crystalizes in quite lengthy molecular dynamics simulations, and moreover, it is in fact a very poor glassformer at large system sizes. Thus, our understanding of crystallization stability of model glassformers is far from complete due to the fact that relatively small system sizes and short time scales have been considered so far.

Polytetrahedral structure and glass-forming ability of simulated Ni-Zr alloys.

Binary Cu-Zr system is a representative bulk glassformer demonstrating high glass-forming ability (GFA). From the first glance, the Ni-Zr system is the most natural object to expect the same behavior because nickel and copper are neighbors in the periodic table and have similar physicochemical properties. However, it is known that the Ni-Zr system has worse GFA than the Cu-Zr one.

Universal self-assembly of one-component three-dimensional dodecagonal quasicrystals.

Using molecular dynamics simulations, we study computational self-assembly of one-component three-dimensional dodecagonal (12-fold) quasicrystals in systems with two-length-scale potentials. Existing criteria for three-dimensional quasicrystal formation are quite complicated and rather inconvenient for particle simulations. So to localize numerically the quasicrystal phase, one should usually simulate over a wide range of system parameters.

Noisy metamolecule: strong narrowing of fluorescence line: reply.

We reply on the comment [Opt. Lett.41, 5821 (2016)10.

Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure.

Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.

Competition of magneto-dipole, anisotropy and exchange interactions in composite multiferroics.

We study the competition of magneto-dipole, anisotropy and exchange interactions in composite three-dimensional multiferroics. Using Monte Carlo simulations we show that magneto-dipole interaction does not suppress the ferromagnetic state caused by the interaction of the ferroelectric matrix and magnetic subsystem. However, the presence of the magneto-dipole interaction influences the order-disorder transition: depending on the strength of magneto-dipole interaction the transition from the ferromagnetic to the superparamagnetic state is accompanied either by the creation of vortices or domains of opposite magnetization.

Noisy metamolecule: strong narrowing of fluorescence line.

We consider a metamolecule consisting of a bosonic mode correlated with a two-level system (TLS): it can be, for example, a plasmonic mode interacting with a quantum dot. We focus on the parameter range where all the correlations are strong and of the same order. The interaction between the bosonic mode is correlated with the TLS, external coherent drive, and dissipation.

Self-assembly of the decagonal quasicrystalline order in simple three-dimensional systems.

Using molecular dynamics simulations we show that a one-component system can be driven to a three-dimensional decagonal (10-fold) quasicrystalline state just by purely repulsive, isotropic and monotonic interaction pair potential with two characteristic length scales; no attraction is needed. We found that self-assembly of a decagonal quasicrystal from a fluid can be predicted by two dimensionless effective parameters describing the fluid structure. We demonstrate stability of the results under changes of the potential by obtaining the decagonal order for three particle systems with different interaction potentials, both purely repulsive and attractive, but with the same values of the effective parameters.

Superattraction mediated by quantum fluctuations of plasmon quasi-continuum.

We investigate the force between a plasmonic nanoparticle and a highly excited two-level system (molecule). Usually van der Waals' force between nanoscale electrically neutral systems is monotonic and attractive at moderate and larger distances and repulsive at small distances. In our system, the van der Waals' force acting on a molecule has a quantum-optical nature.

Electric field control of magnetic properties and magneto-transport in composite multiferroics.

We study magnetic state and electron transport properties of composite multiferroic system consisting of a granular ferromagnetic thin film placed above the ferroelectric substrate. Ferroelectricity and magnetism in this case are coupled by the long-range Coulomb interaction. We show that magnetic state and magneto-transport strongly depend on temperature, external electric field and electric polarization of the substrate.

Hydrodynamic anomalies in supercritical fluid.

Using the molecular dynamics simulations we investigate properties of velocity autocorrelation function of Lennard-Jones fluid at long and intermediate time scales in wide ranges of temperature and density. We show that the amplitudes of both the leading and the subleading time asymptotic terms of velocity autocorrelation function, a1 and a2, show essentially non-monotonic temperature and density dependence. There are two lines on temperature-density plain corresponding to maxima of a1 (a2) along isochors and isotherms situated in the supercritical fluid (hydrodynamic anomalies).

Generalized Sherrington-Kirkpatrick glass without reflection symmetry.

We investigate generalized Sherrington-Kirkpatrick glassy systems without reflection symmetry. In the neighborhood of the transition temperature, we, in general, uncover the structure of the glass state building the full-replica-symmetry-breaking solution. A physical example of the explicitly constructed solution is given.