SIMULATION OF THE FRACTAL METAL FILMS FORMATION

В данной работе методом молекулярной динамики с использованием потенциала сильной связи проведено моделирование процесса молекулярно-лучевой эпитаксии с целью определения закономерностей при формировании фрактальных металлических пленок платины на поверхности родия. Установлена возможность формирования фрактальных структур как в островковых пленках платины на поверхности родия, так и в сплошной пленке. Установлены параметры компьютерного эксперимента, определяющие переход от отдельных островковых пленок к сплошной пленке в указанной системе. С использованием различных программных продуктов Gwyddion и Image Analysis, а также собственной разработки FractalSurface проанализирован диапазон изменения фрактальной размерности при различных условиях молекулярно-динамического эксперимента методом подсчета кубов. Полученные значения фрактальной размерности в целом находятся в приемлемом согласии между собой, однако существует ряд исключений, которые обсуждаются более подробно. Сравнительный анализ получаемых результатов позволяет формулировать рекомендации для методики создания, корректировки и прецизионного контроля при «выращивании» структур с заданной морфологией поверхности. In this work, the molecular dynamics method and the tight-binding potential are used to simulate the process of molecular beam epitaxy in order to determine the regularities in the formation of fractal platinum metal films on the rhodium surface. The possibility of formation of fractal structures both in island platinum films on the rhodium surface and in a continuous film has been established. The parameters of the computer experiment, which determine the transition from individual island films to a continuous film in the indicated system, have been established. Using various software products Gwyddion and Image Analysis, as well as our own software FractalSurface, the range of changes in the fractal dimension has been analyzed under various conditions of a molecular dynamics experiment by the method of cube counting. The obtained values of the fractal dimension are generally in acceptable agreement with each other; however, there is a number of exceptions, which are discussed in more detail. A comparative analysis of the results obtained allows one to formulate recommendations for the methodology for creating, adjusting and precision control when «growing» structures with a given surface morphology.

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Estimating Ag-Cu Nanoalloy Applicability for PCM Data Recording

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.310.47 ◽

2020 ◽

Vol 310 ◽

pp. 47-52

Author(s):

Yuri Ya Gafner ◽

Svetlana L. Gafner ◽

Daria A. Ryzhkova

Keyword(s):

Copper Content ◽

Removal Rate ◽

Tight Binding ◽

Heat Removal ◽

Binding Potential ◽

Chemical Compositions ◽

Internal Structures ◽

Individual Particles ◽

Dynamics Method ◽

Change Memory

The paper studies applicability of individual particles of Ag-Cu nanoalloys as data bits in the next generation memory devices constructed on the phase change memory principle. To fulfill this task, the structure formation was simulated with the molecular dynamics method on cooling from the melt of Ag-Cu nanoparticles of the diameter of 2.0 – 8.0 nm of different chemical compositions (with copper content in the alloy from 10 to 50 percent), based on the modified tight-binding potential (TB-SMA). The authors investigated the influence of the size effects and the heat removal rate on the formation of the clusters structure. The investigation showed that different internal structures can be developed upon cooling from the liquid phase, so there were determined some criteria of their stability. Clusters with copper content of not more than 10% and diameters of more than 6.0 nm were isolated from the entire set of the considered particles.

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Development of Constraint Algorithm for the Number of Electrons in Molecular Orbitals Consisting Mainly 4fAtomic Orbitals of Rare-Earth Elements and Its Introduction to Tight-Binding Quantum Chemical Molecular Dynamics Method

Japanese Journal of Applied Physics ◽

10.1143/jjap.46.2505 ◽

2007 ◽

Vol 46 (4B) ◽

pp. 2505-2509 ◽

Cited By ~ 8

Author(s):

Akira Endou ◽

Hiroaki Onuma ◽

Sun-ho Jung ◽

Ryota Ishimoto ◽

Hideyuki Tsuboi ◽

...

Keyword(s):

Molecular Dynamics ◽

Rare Earth ◽

Rare Earth Elements ◽

Quantum Chemical ◽

Tight Binding ◽

Molecular Orbitals ◽

Molecular Dynamics Method ◽

Quantum Chemical Molecular Dynamics ◽

Dynamics Method

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UNIVERSAL PARAMETER TIGHT-BINDING MOLECULAR DYNAMICS FOR CLUSTERS AND MOLECULES

International Journal of Modern Physics B ◽

10.1142/s0217979292001900 ◽

1992 ◽

Vol 06 (23n24) ◽

pp. 3839-3844 ◽

Cited By ~ 2

Author(s):

Madhu Menon ◽

K.R. Subbaswamy

Keyword(s):

Molecular Dynamics ◽

Tight Binding ◽

Orthogonal Basis ◽

Molecular Dynamics Method ◽

Small Clusters ◽

Dynamics Method ◽

Parameter Scheme

A non-orthogonal basis tight-binding molecular dynamics method, based on Harrison’s universal parameter scheme is described. The method can handle interactions between heteroatoms in a systematic way, and can treat interactions at arbitrary range. Results for small clusters and fullerenes are presented.

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STRUCTURES OF SILICON CLUSTERS

Surface Review and Letters ◽

10.1142/s0218625x96000620 ◽

1996 ◽

Vol 03 (01) ◽

pp. 341-345 ◽

Cited By ~ 4

Author(s):

JUN PAN ◽

ATUL BAHEL ◽

MUSHTI V. RAMAKRISHNA

Keyword(s):

Molecular Dynamics ◽

Characteristic Feature ◽

Size Range ◽

Layer Structure ◽

Tight Binding ◽

Molecular Dynamics Method ◽

Silicon Clusters ◽

Dynamics Method

We determined the structures of silicon clusters in the 11–14-atom size range using the tight-binding molecular dynamics method. These calculations reveal that Si11 is an icosahedron with one missing cap, Si12 is a complete icosahedron, Si13 is a surface-capped icosahedron, and Si14 is a 4-4-4 layer structure with two caps. The characteristic feature of these clusters is that they are all surface.

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Development of SCF-Tight-Binding Quantum Chemical Molecular Dynamics Method and Its Application to Polymer Electrolyte Fuel Cell

ECS Meeting Abstracts ◽

10.1149/ma2006-01/36/1222 ◽

2006 ◽

Keyword(s):

Molecular Dynamics ◽

Fuel Cell ◽

Polymer Electrolyte ◽

Quantum Chemical ◽

Tight Binding ◽

Molecular Dynamics Method ◽

Polymer Electrolyte Fuel Cell ◽

Quantum Chemical Molecular Dynamics ◽

Dynamics Method

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Spectroscopic Ellipsometry and Band Structure of Si1–yCy Alloys Grown Pseudomorphically on Si (001)

MRS Proceedings ◽

10.1557/proc-379-205 ◽

1995 ◽

Vol 379 ◽

Cited By ~ 1

Author(s):

Stefan Zollner ◽

Craig M. Herzinger ◽

John A. Woollam ◽

Subramanian S. Lyer ◽

Adrian P. Powell ◽

...

Keyword(s):

Molecular Dynamics ◽

Shear Stress ◽

Low Temperatures ◽

Molecular Beam ◽

Tight Binding ◽

Analytical Line ◽

Virtual Crystal Approximation ◽

Line Shapes ◽

Dynamics Simulations ◽

Derivatives Of

ABSTRACTWe have measured the dielectric functions of three Si1−yCy, alloys layers (y ≤1.4%) grown pseudomorphically on Si (001) substrates using molecular beam epitaxy at low temperatures. From the numerical derivatives of the measured spectra, we determine the critical point energies E′0 and E1 as a function of y (y ≤ 1.4%) using a comparison with analytical line shapes and analyze these energies in terms of the expected shifts and splittings due to negative hydrostatic pressure, shear stress, and alloying. Our data agree well with the calculated shifts for El, but the E′0 energies are lower than expected. We discuss our results in comparison with recent tight-binding molecular dynamics simulations by Demkov and Sankey (Phys. Rev. B 48, 2207, 1993) prediciting a total breakdown of the virtual-crystal approximation for such alloys.

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STRUCTURAL STABILITY OF Ag AND Ag NANOCLUSTERS WITH A CHANGE IN THE INITIAL MORPHOLOGY

Physical and Chemical Aspects of the Study of Clusters Nanostructures and Nanomaterials ◽

10.26456/pcascnn/2021.13.604 ◽

2021 ◽

pp. 604-611

Author(s):

Дарья Антоновна Рыжкова ◽

Светлана Леонидовна Гафнер ◽

Юрий Яковлевич Гафнер

Keyword(s):

Tight Binding ◽

Thermal Relaxation ◽

Silver Nanoclusters ◽

Binding Potential ◽

Magic Numbers ◽

Structural Transitions ◽

Thermally Induced ◽

Second Moment ◽

Moment Approximation ◽

Dynamics Method

В статье методом молекулярной динамики с использованием модифицированного потенциала сильной связи TB-SMA (second moment approximation of tight-binding) проводится сравнительный анализ характера термически индуцированных структурных переходов в нанокластерах серебра, число атомов в которых соответствует «магическим» числам икосаэдрической структуры, при вариации их начальной морфологии. Показано, что в случае начальной ГЦК конфигурации формирование Ih модификации происходит либо на этапе предварительной термической релаксации, либо в ходе дальнейшего нагрева. При начальной аморфной морфологии характер структурных переходов претерпевает значительные изменения. Так, например, формирующаяся Ih модификация обладает большей стабильностью в области высоких температур и точка плавления нанокластеров смещается на величину более 100 К. Такой эффект обусловлен более плавным изменением удельной потенциальной энергии нанокластера в сравнении со случаем, когда устойчивая Ih конфигурация формируется при низких температурах. Полученные данные могут быть использованы при процессах создания нанокластеров серебра с требуемым внутренним строением. This article provides a comparative analysis of thermally induced structural transitions in silver nanoclusters with a change in their initial morphology. The study was executed by the molecular dynamics method using the modified TB-SMA (second moment approximation of tight-binding) tight binding potential. The number of atoms in nanoclusters corresponds to the icosahedral structure «magic» numbers. It is shown that for nanoclusters with the initial FCC configuration, the Ih modification is formed either at the stage of preliminary thermal relaxation or during further heating. For nanoclusters with an initial amorphous morphology, the nature of structural transitions undergoes significant changes. For example, the formed Ih modification is more stable at high temperatures and the melting point of nanoclusters shifts by more than 100 K. This effect is due to a smoother change in the specific potential energy of the nanocluster in comparison with the case when a stable Ih configuration is formed at low temperatures. The data obtained can be used in processes to create silver nanoclusters with the required internal structure.

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Effect of cooling rate on structural transformations in Ti-Al-V nanoalloy: molecular dynamics study

Journal of Physics Conference Series ◽

10.1088/1742-6596/2052/1/012038 ◽

2021 ◽

Vol 2052 (1) ◽

pp. 012038

Author(s):

N Yu Sdobnyakov ◽

V M Samsonov ◽

V S Myasnichenko ◽

P M Ershov ◽

A N Bazulev ◽

...

Keyword(s):

Molecular Dynamics ◽

Size Effect ◽

Cooling Rate ◽

Tight Binding ◽

Structural Transformations ◽

Rate Effect ◽

Binding Potential ◽

Cooling Rates ◽

Thermally Induced ◽

Local Structures

Abstract Using the isothermal molecular dynamics and the tight-binding potential, crystallization of Ti6Al4V nanodroplets was simulated. The objects of the research consisted of 2869 atoms, including 172 Al atoms and 115 V ones. The OVITO program was employed to recognize local structures and nanophases arisen in the course of cooling nanoalloy with the cooling rates of 0.1 and 0.4 K/ps. We have found that the cooling rate effect on the structure of the Ti6Al4V nanoalloy and the thermally induced structural transformations is much more pronounced than the size effect.

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Оценка влияния икосаэдрических "магических" чисел на термическую стабильность малых нанокластеров серебра

Физика твердого тела ◽

10.21883/ftt.2022.03.52091.245 ◽

2022 ◽

Vol 64 (3) ◽

pp. 313

Author(s):

Д.А. Рыжкова ◽

С.Л. Гафнер ◽

Ю.Я. Гафнер

Keyword(s):

Tight Binding ◽

Thermal Relaxation ◽

Silver Nanoclusters ◽

Binding Potential ◽

Magic Numbers ◽

Structural Transitions ◽

Icosahedral Structure ◽

Thermally Induced ◽

Fcc Phase ◽

Dynamics Method

A comparative analysis of thermally induced structural transitions in silver nanoclusters, the number of atoms of which corresponded to the “magic” numbers of the icosahedral (Ih) structure with variation of their initial morphology, was carried out by the molecular dynamics method using the modified tight-binding potential TB-SMA. It is shown that, in the case of the initial fcc phase, the formation of the Ih modification, depending on the particle size, occurred either at the stage of preliminary thermal relaxation or during further heating. At the initial amorphous morphology, the nature of the structural transitions underwent significant changes. Thus, even in the case of Ag55 clusters, the icosahedral structure was formed only in 50-60% of the experiments performed. Based on the data obtained, it was concluded that to create a stable Ih structure, it is necessary to use the thermal cycling procedure.

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