Pristine monocrystalline molybdenum disulfide (MoS2) possesses high mechanical strength comparable to that of stainless steel. Large-area chemical-vapor-deposited monolayer MoS2 tends be polycrystalline with intrinsic grain boundaries (GBs). Topological defects and size skillfully alter its physical properties in a variety materials; however, the polycrystallinity role played performance emerging single-layer remain largely unknown. Here, using large-scale atomistic simulations, GB...

Understanding fundamental mechanical behaviors of ice-like crystals is importance in many engineering aspects. Herein, characteristics monocrystalline methane hydrate (MMH) and hexagonal ice (Ih) under loads are contrasted by atomistic simulations. Effects strain rate, temperature, crystal orientation, occupancy guest molecules on the properties MMH investigated. Results show that 51262 cages greatly affect strength failure MMH, whereas effect orientation tensile response such as along [100]...

Water ice and gas hydrates can coexist in the permafrost polar regions on Earth universe. However, role of mechanical response ice-contained methane is still unclear. Here, we conduct direct million-atom molecular simulations polycrystalline identify a crossover tensile strength average compressive flow stress due to presence ice. The shear strengths hydrate–hydrate bicrystals are about three times as large those hydrate–ice bicrystals. content, especially below 70%, shows significant effect...

Clathrate hydrates (CHs) are promising molecular structures for versatile applications such as gas capture and storage, cold separation. Understanding the mechanical responses is of importance utilizing predicting stability their formations, but remains very limited. Here, characteristics CHs entrapping a variety molecules investigated by dynamics (MD) simulations. All studied structurally stable host–host hydrogen (H)-bonds yet show distinct host–guest interaction energies under load-free...

Structural evolutions of amorphous hydrates are characterized by an ordering phenomenon, providing molecular insights into understanding physicochemical properties clathrates.

The power-law creep properties of methane hydrates were measured experimentally two decades ago, but their microscopic explanation is still missing. Here we show, using molecular dynamics simulations spanning almost 2 orders magnitude stresses and 3 strain rates, that such emerges in polycrystalline a monatomic water model, suggesting only simplified interactions the concept hydrate polycrystal are needed for behavior to emerge. Damage patterns post-creep suggest strong because damage occurs...

Although both ice and methane hydrates are hydrogen-bonded structures of water molecules, orders magnitude more creep resistant than ice. The power law scaling properties this resistance was shown experimentally two decades ago, but a molecular-scale explanation for these exponents has still been lacking. Using molecular dynamics simulations over almost stresses three strain rates, we show that consistent with the experiments by Durham coauthors in 2003 can emerge from monatomic model. A...

Massive methane hydrates occur on sediment matrices in nature. Therefore, sediment-based hydrate systems play an essential role the society and community, including energy resources, global climate changes, geohazards. However, a fundamental understanding of mechanical properties hydrate–mineral interface is largely limited due to insufficient experimental techniques. Herein, by using large-scale molecular simulations, we show that (silica, kaolinite, Wyoming-type montmorillonite) are...

The mechanical properties of monocrystalline and polycrystalline monolayer black phosphorus (MBP) are systematically investigated using classic molecular dynamic simulations. For MBP, it is found that the shear strain rate, sample dimensions, temperature, atomic vacancies applied statistical ensemble affect behaviour. wrinkled morphology closely connected with direction in-plane shear, dimensions samples, ensembles. Particularly, small samples subjected to loading/unloading deformation along...

A sound knowledge of thermodynamic properties sII hydrates is great importance to understand the stability gas in petroleum pipelines and natural settings. Here, we report direct molecular dynamics (MD) simulations thermal expansion coefficient, compressibility, specific heat capacity C3H8, or tetrahydrofuran (THF), mixtures CH4 CO2, under a wide, relevant range pressure temperature conditions. The were started with guest molecules positioned at cage center hydrate. Annealing additionally...

A sound knowledge of fundamental mechanical properties water ice is crucial importance to address a wide range applications in earth science, engineering, as well sculpture and winter sports, such skating, fishing, climbing, bobsleighs, so on. Here, we report large-scale molecular dynamics (MD) simulations bi- poly-crystalline hexagonal (Ih) under loads. Results show that bicrystals, upon tension, exhibit either brittle or ductile fracture, depending on the microstructure grain boundaries...

The shear failure mechanism of polycrystalline gas hydrates is critical for understanding marine geohazards related to under a changing climate and safe recovery from hydrate reservoirs. Since current experimental techniques cannot resolve the on spatial temporal nanoscale, molecular simulations can assist with proposing substantiating nanoscale mechanisms. Here, we report methane using direct dynamics simulations. Based these simulations, suggest two modes behavior, depending grain sizes,...

Fundamental creep mechanisms of nanocrystalline methane hydrates are revealed, which importance to evaluate the mechanical stability gas hydrate-bearing sediments in both terrestrial and planetological environments.

Gas hydrates play a significant role in the broad areas of energy applications and climate changes. Furthermore, externally applied fields by charged sediments artificial activities are paramount importance for transitions between disordered ordered gas hydrate systems on Earth. Herein, external static electric structural instability mechanical properties methane explored using molecular dynamics simulation methods. Our results show that characteristics such as Young's modulus, strengths,...

Understanding the phase stability of gas hydrates under confinement is fundamental to geological evolutions hydrate systems on Earth. Herein, CH4 and CO2 predicted by machine learning. Three learning models, including support vector machine, random forest, gradient boosting decision tree, are constructed predict confinement. Our results show that prediction accuracy model highest, yet forest lowest among those models in determining confined hydrates. Based their performance predicting...

Self-assembled structures of two-dimensional (2D) materials exhibit novel physical properties distinct from those their parent materials. Herein, the critical role desulfurization on self-assembled structural morphologies molybdenum disulfide (MoS2) monolayer sheets is explored using molecular dynamics (MD) simulations. MD results show that there are differences in atomic energetics MoS2 with different contents. Both free-standing and substrate-hosted diversity morphologies, for example,...

<p indent=0mm>A sound knowledge of surface topography and property natural gas hydrates is great importance to understand the interaction between hydrate particles, or particles with other media such as steels in petroleum pipelines minerals settings. However, a solid effective approach investigation on clathrate remains longstanding challenge. Here, we firstly report characterization THF using atomic force microscopy (AFM). These samples grew from solution liquid drop air confined at...

Atomic force microscopy (AFM) indentation is widely used to determine mechanical parameters of various materials. However, AFM tip may lead phase transition the cold sample in region contact area. It a long-standing challenge that low-temperature phase-change materials (e.g., ice and hydrate) are hardly characterized by AFM, especially for clathrate hydrates. Here, with theoretical analysis numerical simulation, we investigated temperature influence on tetrahydrofuran (THF) hydrate...

Water and methane can stay together under low temperature high pressure in the forms of liquid solutions crystalline solids. From gaseous states to solids or contrary processes, amorphous hydrates occur these evolution scenarios. Herein, mechanical properties are explored for first time bridge gap between responses monocrystalline polycrystalline hydrates. Our results demonstrate that strongly governed by our original proposed order parameter, namely, normalized hydrogen-bond directional...

Self-assembled topological structures of post-processed two-dimensional materials exhibit novel physical properties distinct from those their parent materials. Herein, the critical role desulphurization on self-assembled morphologies molybdenum disulfide ($MoS_2$) monolayer sheets is explored using molecular dynamics (MD) simulations. MD results show that there are differences in atomic energetics $MoS_2$ with different contents. Both free-standing and substrate-hosted diversity such as flat...