Advanced Molecular Dynamics Simulations on the Formation of Transition Metal Nanoparticles

Wang, Lichang; Hudson, George A.

doi:10.5772/36344

Cited by 4 publications

(3 citation statements)

References 104 publications

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“…More technical details are presented in [11]. Here we note that the chemical composition of film, thickness and specific density were obtained using both Rutherford backscattering and nuclear reac- [21], [22]. The gap becomes zero for N=37 Figure 1 shows the Raman spectrum for a − C : F e in the area corresponding to atomic vibrations of the carbon matrix where specific bands D and G manifest themselves.…”

Section: Methodsmentioning

confidence: 99%

Encapsulation of iron atoms between fragments of graphene planes

Siklitskaya¹,

Ivanov-Omskiĭ²,

Chekulaev³

et al. 2015

Nanosist.: fiz. him. mat.

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In this paper, we apply results of analysis of the Raman spectrum from an amorphous carbon film modified with iron (a − C : F e) which leads to construction of clusters containing fragments of graphene and a layer of iron atoms. Such clusters may be candidates for the role of microwave radiation absorbers. For the Raman experiments we performed deposition of a thin film of a − C : F e. Details of the film deposition process, together with the corresponding Raman experiments are presented in this paper. Comparison with a literature model was performed for the intensity ratio of the maxima for specific Raman bands, using the letter D to represent "disorder" and the letter G to represent "graphite". Comparison gives evidence for the existence of nanosize fragments of graphene embedded in an amorphous matrix of the a − C : F e film. The diameter of the fragments is predicted to attain a value of about 1.2 nm. Moreover, in a comparison with experimental data for defective graphite, the position of the maximum of the D band for a− C : F e appeared to be red shifted. This could support the proposition that damping of Raman-active oscillations occurs by an electron gas in fragments of graphene after introduction of iron, e.g. after intercalation. On the basis of these estimates, we modeled a symmetrical polycyclic aromatic hydrocarbon having a similar size and converted it into fragment of a graphene plane by removal of hydrogen atoms occupying the edge states. To preserve symmetry, we placed atoms of iron on top of the fragment, situating them exactly above the centers of hexagons at a certain distance and placed another fragment of graphene on the top of the iron atoms, symmetrically. For a distance of 2.52Åbetween the centers of the hexagon and the iron atom, distortions of carbon-carbon valence bonds and angles were found to be minimal, as shown through optimization of the system's geometry using the Avogadro molecular editor. This result supports an hypothesis of graphene fragments during the growth of an amorphous carbon film modified by simultaneous addition of a dopant metal such as iron. This example may illustrate the stability of a two-dimensional electron gas confined between the fragments.

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Section: Methodsmentioning

confidence: 99%

Encapsulation of iron atoms between fragments of graphene planes

Siklitskaya¹,

Ivanov-Omskiĭ²,

Chekulaev³

et al. 2015

Nanosist.: fiz. him. mat.

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“…However, these models often fall short in their predictive accuracy in real-world scenarios [19]. The use of atomistic molecular dynamics (MD) methodologies has become widespread in the exploration of interfacial thermal properties across a variety of material systems [20][21][22][23][24][25][26]. Chen et al focused on the influence of interface coupling strength on the ITR at Si/SiO 2 interface, utilizing non-equilibrium molecular dynamics (NEMD) [27].…”

Section: Introductionmentioning

confidence: 99%

Thermal transport mechanism of 4H–SiC/SiO₂ heterostructures: a molecular dynamics study

Xiao,

Xing,

Shu

et al. 2023

Phys. Scr.

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Silicon carbide (SiC) is widely used in high-frequency, high-speed, and high-power applications such as power electronics, rail transportation, new energy vehicles, and aerospace. However, the thermal properties of the SiC/SiO2 interface, which is commonly found in SiC-based devices, are not yet fully understood. This study aims to investigate the influence of temperature and interface coupling strength on the interface thermal resistance (ITR) of 4H-SiC/SiO2 using non-equilibrium molecular dynamics simulations. Both crystalline and amorphous SiO2, as well as two interface contact modes (Si-terminated and C-terminated), have also been considered. The results reveal that the ITR of 4H-SiC/SiO2 is significantly affected by the interface coupling strength and contact modes. Under strong interface coupling conditions, the ITR for Si-terminated and C-terminated contacts modes of 4H-SiC/SiO2 interfaces are 8.077 × 10−10 m2KW−1 and 6.835 × 10−10 m2KW−1, respectively. However, under weak interface coupling conditions, these values increase to 10.142 × 10−10 m2KW−1 and 7.785 × 10−10 m2KW−1, respectively. Regardless of whether SiO2 is crystalline or amorphous, the ITR of the 4H-SiC/SiO2 interface exhibits a similar trend with increasing temperature (from 300 to 700 K). Additionally, the ITR of the amorphous SiO2 interface is smaller than that of the crystalline SiO2 interface under both strong and weak coupling conditions. To gain insights into the heat transport mechanism, the phonon density of states was analyzed to examine the phonon spectral characteristics under varying coupling strengths. These findings have implications for enhancing the thermal management and heat dissipation of SiC devices, providing a framework for controlling interface phonon scattering, and informing the thermal design of nanodevices.

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“…FMO-MD was originally implemented by combining ABINIT-MP [4], an FMO program, and PEACH [5], an MD program. The resultant FMO-MD simulator is called the PEACH/ABINIT-MP system [6][7] [8]. For further details, readers are referred to reference [9] for fragmentation methods in general, to reference [10] for FMO, and to reference [8] for FMO-MD.…”

Section: Introductionmentioning

confidence: 99%

Dynamic fragmentation with static fragments (DF/SF) algorithm designed for <i>ab initio</i> fragment molecular orbital-based molecular dynamics (FMO-MD) simulations of polypeptides

Komeiji

Fujiwara

Okiyama

et al. 2013

CBIJ

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The ab initio fragment molecular orbital-based molecular dynamics (FMO-MD) method was extended for simulation of solvated polypeptides by the introduction of an algorithm named dynamic fragmentation with static fragments (DF/SF). In FMO-MD, the force acting on each nucleus is calculated by the FMO method, which requires fragmentation of the simulated molecule. The fragmentation data must be redefined, depending on the time-dependent change of the molecular configuration, and the DF/SF algorithm governs this redefinition. In the DF/SF algorithm, some fragments are manually classified as static and unchanged, while others are considered dynamic and subject to change. Various options of the algorithm were implemented in the ABINIT-MP program. The options were tested and discussed as they applied to FMO-MD simulations of the solvated (Gly) 2 dipeptide, in which the two amino acid residues of the peptide were regarded as static (invariable) while surrounding water molecules were regarded as dynamic (variable). Future prospects for the FMO-MD simulation of biopolymers are discussed based upon the tests of the DF/SF algorithm.

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Advanced Molecular Dynamics Simulations on the Formation of Transition Metal Nanoparticles

Cited by 4 publications

References 104 publications

Encapsulation of iron atoms between fragments of graphene planes

Encapsulation of iron atoms between fragments of graphene planes

Thermal transport mechanism of 4H–SiC/SiO₂ heterostructures: a molecular dynamics study

Dynamic fragmentation with static fragments (DF/SF) algorithm designed for <i>ab initio</i> fragment molecular orbital-based molecular dynamics (FMO-MD) simulations of polypeptides

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Advanced Molecular Dynamics Simulations on the Formation of Transition Metal Nanoparticles

Cited by 4 publications

References 104 publications

Encapsulation of iron atoms between fragments of graphene planes

Encapsulation of iron atoms between fragments of graphene planes

Thermal transport mechanism of 4H–SiC/SiO2 heterostructures: a molecular dynamics study

Dynamic fragmentation with static fragments (DF/SF) algorithm designed for <i>ab initio</i> fragment molecular orbital-based molecular dynamics (FMO-MD) simulations of polypeptides

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Thermal transport mechanism of 4H–SiC/SiO₂ heterostructures: a molecular dynamics study