[Mechanical response of Au (001) nanoplate under uniaxial stress condition along [100] direction] Under mechanical loading, metal nanoplates fail via elastic instability rather than the yield strength. As a result, we observed a unique “smaller is weaker” trend. We provided numerical and theoretical evidence to show that the nanoplates exhibit an intermediate […]
[Stress-drop due to phonon scattering around dislocation core while it is in motion] Unlike continuum, the motion of dislocation in nanoscale system induces unusual phenomenon. Through atomistic simulations, we observed that the internal effective stress of the system is always smaller than the externally applied stress during the dislocation motion. And we defined this unusual […]
Shape-memory alloys (SMAs) are a rare class of metal compound that after a huge mechanical strain can, on heating, recover their original atomic configuration. In the many useful applications of SMAs, the most studied material is NiTi (nitinol). The understanding on the NiTi properties in nano-scale calculations is still lacking. Here, we present a first-principles […]
Good cyclability is essential for the potential application of cathode materials. Here, we investigate the structural stability of two-dimensional (2D) Li-layered and three-dimensional (3D) structured polymorphs of Li2FeSiO4 and Li2MnSiO4 using the density functional theory calculation. We find that all 2D Li-layered polymorphs of both materials are unstable upon full-delithiation owing to layer exfolilation, which […]
Density Functional Theory (DFT) calculations are one of the most accurate and expensive simulations to investigate nanomaterials. Electronic properties, such as band structure of materials are widely studied by DFT. The band structure and its change due to applied strain of an MoS2 monolayer are conducted as an example. An MoS2 monolayer show direct band […]
According to Born (1940) and Hill (1977), a material becomes intrinsically unstable when its elastic moduli tensor (or modified one) loses its positive definiteness. It is true for bulk materials, but it is not exactly true in the case of nanowires, due to the so-called surface effect. The surface effect increases as the thickness of […]
According to continuum plate theory, the elastic stress waves propagate in plates in the form of Lamb waves due to stress-free surfaces. Through MD, we can compare the Lamb waves in nanoscale plate to those in continuum plate. MD is a useful method to evaluate the validity and limitation of solid mechanics theories for nanoscale […]
Nanowires, both metallic and semiconducting, will be utilized for various NEMS applications, including mass, force and pressure sensing, next generation wireless applications, etc. One key issue for nanowire-based NEMS is that their Q-factors, due to surface effects degrade considerably with decreasing nanowire size. We have recently demonstrated using classical molecular dynamics that mechanical strain […]
Besides edge effects, graphene nanoresonators are expected to lose energy through interlayer friction effects, and the quality of attachment through van der Waal’s forces to the underlying (model silicon) substrate. We have quantified these losses as compared to an ideal graphene monolayer, as seen below. The key result is that, if intrinsic interlayer friction and […]
Interestingly, the study also found that the free edges of the graphene sheet often had the largest vibrational amplitudes during resonance. To verify this, finite element simulations of the graphene sheet were performed; by introducing non-uniform stresses in the suspended graphene sheet through application of both an in-plane stretch and an in-plane rotation, the authors […]