Search Results (23)

In the present study, molecular dynamics simulations with three interatomic potentials (Polymer Consistent Force Field, Adaptive Intermolecular Reactive Empirical Bond Order, and Tersoff) are employed to investigate strain-dependent interfacial thermal resistance across one-dimensional to two-dimensional junctions. Carbon nanotube–graphene junctions exhibit exceptionally low interfacial resistances (1.69–2.37 × 10⁻¹⁰ K·m²/W at 300 K)—two to three orders of magnitude lower than conventional metal–dielectric interfaces. Strain-dependent behavior is highly potential-dependent, with different potentials showing inverse, positive, or minimal strain sensitivity. Local phonon density of states analysis with Tersoff reveals that strain-induced spectral redistribution in graphene toward lower frequencies enhances phonon coupling with carbon nanotube modes. Temperature significantly affects resistance, with 37–59% increases at 10 K compared to 300 K due to long-wavelength phonon scattering. Boron nitride nanotube–hexagonal boron nitride nanosheet junctions exhibit 60% higher resistance (3.2 × 10⁻¹⁰ K·m²/W) with temperature-dependent strain behavior and spacing-insensitive performance. Interfacial resistance is independent of pillar height, confirming junction-dominated transport. The discovery of exceptionally low interfacial resistances and material-specific strain responses enables the engineering of thermally switchable devices and mechanically robust thermal pathways. These findings directly address critical challenges in next-generation flexible electronics where devices must simultaneously manage high heat fluxes while maintaining thermal performance under repeated mechanical deformation. Full article

Silicon-based MEMS devices are essential in extreme radiation environments but suffer progressive reliability degradation from irradiation-induced defects. Here, the generation, aggregation, and clustering of defects in single-crystal silicon were systematically investigated through molecular dynamics (MD) simulations via employing a hybrid Tersoff–ZBL potential that was validated by nanoindentation and transmission electron microscopy. The influences of the primary knock-on atom energy, temperature, and pre-strain state on defect evolution were quantified in detail. Frenkel defects were found to cause a linear reduction in the Young’s modulus and a nonlinear decline in thermal conductivity via enhanced phonon scattering. To link atomic-scale damage with device-level performance, MD-predicted modulus degradation was incorporated into finite element (FE) models of a sensing diaphragm. The FE analysis revealed that modulus reductions result in nonlinear increases in deflection and stress concentration, potentially impairing sensing accuracy. This integrated MD–FE framework establishes a robust, physics-based approach for predicting and mitigating irradiation damage in silicon-based MEMS operating in extreme environments. Full article

Advanced nanocomposite membranes incorporate nanomaterials within a polymer matrix to augment the mechanical strength of the resultant product. Characterizing these membranes through molecular modeling necessitates specialized approaches to accurately capture the length scales, time scales, and structural complexities inherent in polymers. To address these requirements, an efficient simulation protocol is proposed, utilizing coarse-grained (CG) molecular dynamics simulations to examine the mechanical properties of polyethylene/single-walled carbon nanotube (PE/SWCNT) composites. This methodology integrates CG potentials derived from the statistical associating fluid theory (SAFT-$\gamma$ Mie) equation of state and a modified Tersoff potential as a model for SWCNTs. A qualitative correspondence with benchmark classical all-atom models, as well as available experimental data, is observed, alongside enhanced computational efficiency. Employing this CG model, the focus is directed at exploring the mechanical properties of PE/SWCNT composites under both tensile and compressive loading conditions. The investigation covered the influence of SWCNT size, dispersion, and weight fraction. The findings indicate that although SWCNTs enhance the mechanical strength of PE, the extent of enhancement marginally depends on the dispersion, filler size, and weight fraction. Fracture strengths may be elevated by 20% with a minor incorporation of SWCNTs. Under compression, the incorporation of SWCNTs into the composites results in a transformation from brittle to tough materials. These insights contribute to the optimization of PE/SWCNT composites, emphasizing the importance of considering multiple factors to fine-tune the desired mechanical performance. Full article

The unique properties of graphene have attracted the interest of researchers from various fields, and the discovery of graphene has sparked a revolution in materials science, specifically in the field of two-dimensional materials. However, graphene synthesis’s costly and complex process significantly impairs researchers’ endeavors to explore its properties and structure experimentally. Molecular dynamics simulation is a well-established and useful tool for investigating graphene’s atomic structure and dynamic behavior at the nanoscale without requiring expensive and complex experiments. The accuracy of the molecular dynamics simulation depends on the potential functions. This work assesses the performance of various potential functions available for graphene in mechanical properties prediction. The following two cases are considered: pristine graphene and pre-cracked graphene. The most popular fifteen potentials have been assessed. Our results suggest that diverse potentials are suitable for various applications. REBO and Tersoff potentials are the best for simulating monolayer pristine graphene, and the MEAM and the AIREBO-m potentials are recommended for those with crack defects because of their respective utilization of the electron density and inclusion of the long-range interaction. We recommend the AIREBO-m potential for a general case of classical molecular dynamics study. This work might help to guide the selection of potentials for graphene simulations and the development of further advanced interatomic potentials. Full article

Quasi-hexagonal-phase fullerene (qHPC₆₀) is an asymmetrically ordered arrangement of fullerene in the two-dimensional plane, which has been synthesized recently. In this study, we performed a comprehensive investigation of the anisotropic mechanical properties of a qHPC₆₀/graphene composite by means of molecular dynamics simulations. We assessed the mechanical properties of the 2D torsion-angle fullerene model with three force-fields: AIREBO, REAXFF, and TERSOFF. The results of the uniaxial tensile tests show that while the variations in fracture stress and fracture strain, with respect to pre-crack size, had similar trends for the three force-fields, AIREBO was more sensitive than REAXFF. The presence of cracks degraded the mechanical properties. Simulations of tensile tests on the qHPC₆₀/graphene composite revealed that the graphene substrate significantly increased mechanical strength. Our results suggest qHPC₆₀ holds various promising implications for composites. Full article

Selecting an appropriate empirical interatomic potential is essential for accurately describing interatomic interactions and simulating the friction and wear of graphene. Four empirical potentials—Tersoff, REBO, AIREBO, and LCBOP—were employed in molecular dynamics simulations to study the wear process of graphene at the atomic scale. The frictional process of graphene was found to be divisible into three distinct phases: elastic deformation, plastic deformation, and wear. Using a progressively increasing load method, the critical load for each phase of graphene under four different empirical potentials was identified. Furthermore, the formation of Stone–Wales (SW) defects, bond distribution, bond breaking and healing, and wrinkle formation were analyzed in detail. Finally, a comparison was made with previous experimental results regarding friction coefficient and wear morphology. Full article

Due to their unique properties, carbon nanotubes (CNTs) are finding a growing number of applications across multiple industrial sectors. These properties of CNTs are subject to influence by numerous factors, including the specific chiral structure, length, type of CNTs used, diameter, and temperature. In this topic, the effects of chirality, diameter, and length of single-walled carbon nanotubes (SWNTs) on the thermal properties were studied using the reverse non-equilibrium molecular dynamics (RNEMD) method and the Tersoff interatomic potential of carbon–carbon based on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). For the shorter SWNTs, the effect of chirality on the thermal conductivity is more obvious than for longer SWNTs. Thermal conductivity increases with increasing chiral angle, and armchair SWNTs have higher thermal conductivity than that of zigzag SWNTs. As the tube length becomes longer, the thermal conductivity increases while the effect of chirality on the thermal conductivity decreases. Furthermore, for SWNTs with longer lengths, the thermal conductivity of zigzag SWNTs is higher than that of the armchair SWNTs. Thermal resistance at the nanotube–nanotube interfaces, particularly the effect of CNT overlap length on thermal resistance, was studied. The simulation results were compared with and in agreement with the experimental and simulation results from the literature. The presented approach could be applied to investigate the properties of other advanced materials. Full article

Beryllium finds widespread applications in nuclear energy, where it is required to service under extreme conditions, including high-dose and high-dose rate radiation with constant bombardments of energetic particles leading to various kinds of defects. Though it is generally known that defects give rise to mechanical degradation, the quantitative relationship between the microstructure and the corresponding mechanical properties remains elusive. Here we have investigated the mechanical properties of imperfect hexagonal close-packed (HCP) beryllium via means of molecular dynamics simulations. We have examined the beryllium crystals with void, a common defect under in-service conditions. We have assessed three types of potentials, including MEAM, Finnis–Sinclair, and Tersoff. The volumetric change with pressure based on MEAM and Tersoff and the volumetric change with temperature based on MEAM are consistent with the experiment. Through cross-comparison on the results from performing hydrostatic compression, heating, and uniaxial tension, the MEAM type potential is found to deliver the most reasonable predictions on the targeted properties. Our atomistic insights might be helpful in atomistic modeling and materials design of beryllium for nuclear energy. Full article

Silicon carbide (SiC) is a promising material for thermoelectric power generation. The characterization of thermal transport properties is essential to understanding their applications in thermoelectric devices. The existence of stacking faults, which originate from the “wrong” stacking sequences of Si–C bilayers, is a general feature of SiC. However, the effects of stacking faults on the thermal properties of SiC are not well understood. In this study, we evaluated the accuracy of Tersoff, MEAM, and GW potentials in describing the thermal transport of SiC. Additionally, the thermal conductivity of 3C/4H-SiC nanowires was investigated using non-equilibrium molecular dynamics simulations (NEMD). Our results show that thermal conductivity exhibits an increase and then saturation as the total lengths of the 3C/4H-SiC nanowires vary from 23.9 nm to 95.6 nm, showing the size effect of molecular dynamics simulations of the thermal conductivity. There is a minimum thermal conductivity, as a function of uniform period length, of the 3C/4H-SiC nanowires. However, the thermal conductivities of nanowires weakly depend on the gradient period lengths and the ratio of 3C/4H. Additionally, the thermal conductivity of 3C/4H-SiC nanowires decreases continuously from compressive strain to tensile strain. The reduction in thermal conductivity suggests that 3C/4H-SiC nanowires have potential applications in advanced thermoelectric devices. Our study provides insights into the thermal transport properties of SiC nanowires and can guide the development of SiC-based thermoelectric materials. Full article

Silicon carbide is successfully implemented in semiconductor technology; it is also used in systems operating under aggressive environmental conditions, including high temperatures and radiation exposure. In the present work, molecular dynamics modeling of the electrolytic deposition of silicon carbide films on copper, nickel, and graphite substrates in a fluoride melt is carried out. Various mechanisms of SiC film growth on graphite and metal substrates were observed. Two types of potentials (Tersoff and Morse) are used to describe the interaction between the film and the graphite substrate. In the case of the Morse potential, a 1.5 times higher adhesion energy of the SiC film to graphite and a higher crystallinity of the film was observed than is the case of the Tersoff potential. The growth rate of clusters on metal substrates has been determined. The detailed structure of the films was studied by the method of statistical geometry based on the construction of Voronoi polyhedra. The film growth based on the use of the Morse potential is compared with a heteroepitaxial electrodeposition model. The results of this work are important for the development of a technology for obtaining thin films of silicon carbide with stable chemical properties, high thermal conductivity, low thermal expansion coefficient, and good wear resistance. Full article

Silicon carbide (SiC) materials are widely applied in the field of nuclear materials and semiconductor materials due to their excellent radiation resistance, thermal conductivity, oxidation resistance, and mechanical strength. The molecular dynamics (MD) simulation is an important method to study the properties, preparation, and performance of SiC materials. It has significant advantages at the atomic scale. The common potential functions for MD simulations of silicon carbide materials were summarized firstly based on extensive literatures. The key parameters, complexity, and application scope were compared and analyzed. Then, the MD simulation of SiC properties, preparation, and performance was comprehensively overviewed. The current studies of MD simulation methods and applications of SiC materials were systematically summarized. It was found that the Tersoff potential was the most widely applied potential function for the MD simulation of SiC materials. The construction of more accurate potential functions for special application fields was an important development trend of potential functions. In the MD simulation of SiC properties, the thermal properties and mechanical properties, including thermal conductivity, hardness, elastic modulus, etc., were mainly studied. The correlation between MD simulations of microscopic processes and the properties of macroscopic materials, as well as the methods for obtaining different property parameters, were summarized. In the MD simulation of SiC preparation, ion implantation, polishing, sputtering, deposition, crystal growth, amorphization, etc., were mainly studied. The chemical vapor deposition (CVD) and sintering methods commonly applied in the preparation of SiC nuclear materials were reported rarely and needed to be further studied. In the MD simulation of SiC performance, most of the present studies were related to SiC applications in the nuclear energy research. The irradiation damage simulation in the field of nuclear materials was studied most widely. It can be found that SiC materials in the field of nuclear materials study were a very important topic. Finally, the future perspective of MD simulation studies of SiC materials were given, and development suggestions were summarized. This paper is helpful for understanding and mastering the general method of computation material science aimed at the multi-level analysis. It also has a good reference value in the field of SiC material study and MD method study. Full article

Molecular dynamics simulations using Tersoff potential were performed in order to study the evolution of the atomic packing structures, loading states on the atoms, and tensile tests, as well as the thermal properties of Si/Ge core–shell nanowires with different core–shell structures and ratios at different temperatures. Potential energy and pair distribution functions indicate the structural features of these nanowires at different temperatures. During uniaxial tensile testing along the wire axis at different temperatures, different stages including elasticity, plasticity, necking, and fractures are characterized through stress–strain curves, and Young’s modulus, as well as tensile strength, are obtained. The packing patterns and Lode–Nadai parameters reveal the deformation evolution and different distributions of loading states at different strains and temperatures. The simulation results indicate that as the temperature increases, elasticity during the stretching process becomes less apparent. Young’s modulus of the Si/Ge core–shell nanowires at room temperature show differences with changing core–shell ratios. In addition, the Lode–Nadai parameters and atomic level pressures show the differences of these atoms under compression or tension. Temperature and strain significantly affects the pressure distribution in these nanowires. The phonon density of states, when varying the composition and strain, suggest different vibration modes at room temperature. The heat capacities of these nanowires were also determined. Full article

Stanene, composed of tin atoms, is a member of 2D-Xenes, two-dimensional single element materials. The properties of the stanene can be changed and improved by applying deformation, and it is important to know the range of in-plane deformation that the stanene can withstand. Using the Tersoff interatomic potential for calculation of phonon frequencies, the range of stability of planar stanene under uniform in-plane deformation is analyzed and compared with the known data for graphene. Unlike atomically flat graphene, stanene has a certain thickness (buckling height). It is shown that as the tensile strain increases, the thickness of the buckled stanene decreases, and when a certain tensile strain is reached, the stanene becomes absolutely flat, like graphene. Postcritical behaviour of stanene depends on the type of applied strain: critical tensile strain leads to breaking of interatomic bonds and critical in-plane compressive strain leads to rippling of stanene. It is demonstrated that application of shear strain reduces the range of stability of stanene. The existence of two energetically equivalent states of stanene is shown, and consequently, the possibility of the formation of domains separated by domain walls in the stanene is predicted. Full article

A computational approach for creating realistically structured carbon nanotubes is presented to enable more accurate and impactful multi-scale modeling and simulation techniques for nanotube research. Much of the published literature to date involving computational modeling of carbon nanotubes simplifies their structure as being long and straight, and often existing as isolated individual nanotubes. However, imagery of nanotubes has shown over several decades that nanotubes agglomerate together and exhibit looping and curvature due both to inter- and intra-nanotube attraction. The research presented in this paper leverages multi-scale simulations consisting of a simple bead-spring model for initial nanotube relaxation followed by a differential geometry approach to create an atomic representation of carbon nanotubes, and then finalized with molecular dynamics simulations using the Tersoff potential model for carbon that allows dynamic bonding and cleavage. The result is atomically accurate representations of carbon nanotubes that exist as single nanotubes, or as clusters of multiple nanotubes. The presented approach is demonstrated using (5,5) single-walled carbon nanotubes. The synthesized nanotubes are shown to relax into the curving and looping structures observed in transmission or scanning electron microscopy, but also exhibit nano-scale defects due to buckling, crimping, and twisting that are resolved during the molecular dynamics simulations. These features locally compromise the desired strength characteristics of nanotubes and therefore the presented procedure will enable more accurate modeling and simulation of nanotubes in subsequent research by representing them less as the theoretically straight and independent entities, but as realistically imperfect. Full article

Evaluation of the entropy from molecular dynamics (MD) simulation remains an outstanding challenge. The standard approach requires thermodynamic integration across a series of simulations. Recent work Nicholson et al. demonstrated the ability to construct a functional that returns excess entropy, based on the pair correlation function (PCF); it was capable of providing, with acceptable accuracy, the absolute excess entropy of iron simulated with a pair potential in both fluid and crystalline states. In this work, the general applicability of the Entropy Pair Functional Theory (EPFT) approach is explored by applying it to three many-body interaction potentials. These potentials are state of the art for large scale models for the three materials in this study: Fe modelled with a modified embedded atom method (MEAM) potential, Cu modelled with an MEAM and Si modelled with a Tersoff potential. We demonstrate the robust nature of EPFT in determining excess entropy for diverse systems with many-body interactions. These are steps toward a universal Entropy Pair Functional, EPF, that can be applied with confidence to determine the entropy associated with sophisticated optimized potentials and first principles simulations of liquids, crystals, engineered structures, and defects. Full article