Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from con...

The configuration of graphene nano-ribbon (GNR) assembly on carbon nanotube (CNT) and sphere is studied through theoretical modeling and molecular simulation. The GNR can spontaneously wind onto the CNT due to van der Waals (vdW) interaction and form two basic configurations: helix and scroll. The final configuration arises from the competition among three energy terms: the bending energy of th...

A force field is proposed for the flexible metal-organic framework MIL-53(Al), which is calibrated using density functional theory calculations on nonperiodic clusters. The force field has three main contributions: an electrostatic term based on atomic charges derived with a modified Hirshfeld-I method, a van der Waals (vdW) term with parameters taken from the MM3 model, and a valence force fie...

Van der Waals (vdW) heterostructures are expected to play a key role in next-generation electronic and optoelectronic devices. In this study, the band alignment of a vdW heterostructure with 2D polar materials was studied using first-principles calculations. As a model case study, single-sided fluorographene (a 2D polar material) on insulating (h-BN) and metallic (graphite) substrates was inves...

van der Waals (vdW) forces, despite being relatively weak, hold the layers together in transition metal dichalcogenides (TMDs) and play a key role in their band structure evolution, hence profoundly affecting their physical properties. In this work, we experimentally probe the vdW interactions in MoS2 and other TMDs by measuring the valence band maximum (VBM) splitting (Δ) at K point as a funct...

Van der Waals (vdW) interactions are important in numerous physical, chemical, and biological systems. However, traditional density functional theory (DFT) within local or semi-local approximations can hardly treat this interaction. Among various attempts to handle vdW interactions in DFT, semiempirical correction methods are known to present the advantages of low additional computational costs...

The accurate determination of stacking fault energies (SFE) and associated restoring forces is important for understanding plastic deformation, especially the dislocation emission and motion in metals. In this work, we use density-functional theory (DFT) calculations to, systematically study the all-dimension relaxed atomic models of Mg crystal slip, with a special focus on the “subslip modes” ...

Abstract With the outstanding mechanical properties, van der Waals (vdW) materials have attracted extensive attention in research of straintronics past decade. In this perspective, we first review recent progresses with vdW based on three different lattice deformation modes, i.e., in-plane strain, out-of-plane and heterostrain. Then discuss current technique challenges field, finally provide ou...

Using first principle methods, we study the mechanical properties of monolayer and bilayer graphene with 50% and 100% coverage of hydrogen. We employ the vdW-DF, vdW-DF-C09x, and vdW-DF2-C09x van der Waals functionals for the exchange correlation interactions that give significantly improved interlayer spacings and energies. We also use the PBE form for the generalized gradient corrected exchan...

This paper gives a review of existing models used by other authors aiming at modeling micromanipulation tasks. It introduces the distinction between surface forces, which act even at distance (van der Waals (VDW), capillary and electrostatic forces) and contact forces, which are closely related to deformation and adhesion. Moreover, it presents our work on VDW and capillary forces: compared to ...