Deposition of a thin film consisting of alternating dense and porous layers is modeled via classical molecular dynamics. The structural parameters of the film are calculated. In modeling the annealing of the deposited film, the concentration of main point defects was found to fall appreciably in all layers of the film. Based on correlations between the density and the refractive index, it is established that the refractive index varies from 1.3 to 1.49, reaching its minimum value in the most porous layers. Such layers can be used in designing multilayer optical coatings that allow light transmission and reflection within specified wavelength ranges.

This paper proposes, and practically implements, a technique for finding equivalent frequencies, which are attributed to the atmospheric optical depths measured by a two-channel wideband radiometric system in the millimeter wavelength range. Establishment of the equivalent frequency (averaged over the frequency response of the system) in the corresponding atmospheric transparency window makes it possible to relate wideband measurements of the optical depth with narrowband radiometric measurements used in standard calculations of integral humidity. The search for equivalent frequencies is based on a comparison of experimental data on the effective transparency in the millimeter wavelength range and integral humidity of the atmosphere by simulation of a real atmosphere using the MPM Liebe model. The developed method of consistent determination of humidity and transparency of the atmosphere in the millimeter wavelength range can be used for both millimeter-wave radioastronomy and high-performance space telecommunications. In particular, the method specifies the spectral characteristics of the measured atmospheric transparency for the studied radio astronomy site and estimates the astroclimate conditions.

Предложена модель, описывающая влияние наночастиц на атомистическую структуру напыляемых тонких пленок. Модель основана на развитом ранее методе молекулярно-динамического моделирования процесса напыления тонких оптических покрытий и применена к пленкам диоксида кремния. Наночастица предполагается неподвижной, ее взаимодействие с атомами описывается сферически симметричным потенциалом. Структура пленки вблизи наночастицы исследуется с помощью радиальных функций распределения. Показано, что поведение этих функций около наночастицы существенно отличается для случаев высокоэнергетического и низкоэнергетического напыления. A model describing the effect of nanoparticles on the structure of thin films structure is proposed. The model is based on the previously developed molecular dynamics method of thin film deposition simulation and is applied to the study of silicon dioxide thin films. A nanoparticle is considered as a fixed object whose interaction with film atoms is described by a spherical symmetric potential. Radial distribution functions are used to study the film structure near the nanoparticle. It is shown that the behavior of these functions is essentially different near nanoparticles in the cases of high-energy and low-energy deposition processes.

We have analyzed the artificial pulsations detected in several cases in the hertz range in terms of the eastern electrojet dynamics. The pulsations were detected in 30% cases of pulse HF wave impact on the ionosphere during an experiment on modulated ionosphere heating at the Space Plasma Exploration by Active Radar (SPEAR) facility (Spitsbergen Archipelago) in November 2013. The pulsations occur when the polar edge of the eastern electrojet approaches the assumed region of influence on the ionosphere due to the northward drift of the electrojet or its extension with increased intensity. The pulsations vanish when the electrojet moves away from the influenced region, drifting southward. The beginning of pulsations is delayed by several minutes with respect to the starting of the HF transmitter. The pulsations are observed only in one of the horizontal components of the geomagnetic field at a distance of 50 km from the SPEAR facility, and they vanished at a distance of about 1300 km.

Excitation of electromagnetic fields at extremely low and lower frequencies in the near-field zone of the Earth–ionosphere waveguide is considered. Variations in the field amplitude in the lower part of the extremely low frequency (ELF) range and lower frequencies are experimentally determined under different geophysical conditions in the absence of variations in the ultralow frequency (ULF) range. The effects related to such variations are analyzed with the aid of theoretical calculations that show significant effect of ionosphere in the near-field zone at relatively low terrestrial conduction.

Влияние ионосферы на возбуждение электромагнитного поля диапазона КНЧ и более низких частот в ближней зоне© Е.Д

The phase velocities of TE and TEM waves at frequencies of 1017 and 3017 Hz, as well as the effect of precipitations during auroras on the velocities, are estimated in the Earth–ionosphere waveguide on the basis of observations of electromagnetic fields of an ionospheric source in experiments on modification of the lower ionosphere by a modulated high-power short-wave signals performed by the Arctic and Antarctic Research Institute (AARI) at the EISCAT/Heating test bench in October 2016. Probable electron density profiles in the plane-stratified ionosphere are retrieved from the numerical solution of a wave equation, which are used for the calculation of the phase velocities close to measured ones.

Кольца, состоящие из различного числа атомов, являются основным структурным элементом во многих неупорядоченных веществах. В настоящей статье представлен параллельный алгоритм получения приближенной функции распределения колец по числу атомов, основанный на методе Монте-Карло. Алгоритм применен к кластерам диоксида кремния, содержащим до миллиона атомов. Исследована эффективность алгоритма, как функция числа используемых вычислительных ядер, вплоть до 1024. The rings consisting of various number of atoms are basic structural elements in many disordered solids. In this paper, a parallel algorithm for calculating an approximate ring distribution function by the number of atoms is proposed. The algorithm is based on the Monte Carlo method and is applied to SiO$_2$ clusters consisting of up to $10^6$ atoms. The efficiency of the algorithm is studied using up to 1024 computational cores.

Предложены методы расчета потерь механической энергии в твердых материалах на основе моделирования методом молекулярной динамики внешнего воздействия и последующей релаксации системы. Рассчитывается обратная добротность и фурье-образ обратной добротности на частоте, равной обратному времени релаксации системы. Для обратной добротности получена оценка сверху, равная $10^{-4}$, что находится в интервале экспериментальных значений; для фурье-образа обратной добротности получена оценка сверху, равная $10^{-2}$. Two methods to estimate the mechanical energy losses in solid materials are proposed. These methods are based on the molecular dynamics simulation of external actions on the body's structure, followed by its relaxation. The inverse quality factor and its Fourier transform are estimated on the frequency equal to the reverse time of relaxation. The inverse quality factor is estimated from above by $10^{-4}$, which corresponds to experimental data.The Fourier transform is estimated from above by $10^{-2}$.

Предложен алгоритм расчета шероховатости поверхности тонких пленок, напыляемых в рамках численных экспериментов. Алгоритм применен к атомистическим кластерам диоксида кремния с характерным размером до 70 нм. Напыление пленки на подложку проводится с использованием метода, развитого ранее на основе классической молекулярной динамики с силовым полем DESIL, созданным специально для моделирования высокоэнергетических процессов напыления. Анализируется зависимость шероховатости от параметров алгоритма и от параметров напыления - температуры подложки и энергии осаждаемых атомов кремния. An algorithm of surface roughness calculation for the thin film atomistic clusters obtained in numerical experiments is proposed. The algorithm is applied to silicon dioxide films. The thickness of deposited films is up to 70 nm. The deposition process simulation is performed using the classical molecular dynamics method with the DESIL force field developed earlier specially for high-energy deposition simulation. The dependence of surface roughness on the algorithm parameters, the temperature of the substrate, and the energy of deposited silicon atoms is studied.