Graphene, a two dimensional (2D) carbon sheet, acquires many of its amazing properties from the Dirac point nature electronic structures with negligible spin-orbit coupling. Extending to 3D space, graphene networks negative curvature, called Mackay-Terrones crystals (MTC), have been proposed and experimentally explored, yet their topological remain be discovered. Based on first-principle calculations, we report an all-carbon MTC topologically non-trivial states by exhibiting node-lines in...

MXenes are a set of two-dimensional transition metal carbides and nitrides that offer many potential applications in energy storage electronic devices. As an important parameter to design new devices, we investigate the work functions bare their functionalized ones with F, OH, O chemical groups using first-principles calculations. From our calculations, it turns out OH terminated attain ultralow between 1.6 2.8 eV. Moreover, depending on type metal, F or functionalization affects increasing...

Two-dimensional (2D) topological insulators (TIs) have been recognized as a new class of quantum state matter. They are distinguished from normal 2D with their nontrivial band-structure topology identified by the ${Z}_{2}$ number protected time-reversal symmetry (TRS). TIs intriguing spin-velocity locked conducting edge states and insulating properties in bulk. In states, electrons opposite spins propagate directions backscattering is fully prohibited when TRS conserved. This leads to...

Using a set of first-principles calculations, we studied the electronic structures two-dimensional transition metal carbides and nitrides, so called MXenes, functionalized with F, O, OH. Our projected band electron localization function analyses reveal existence nearly free (NFE) states in variety MXenes. The NFE are spatially located just outside atomic structure MXenes extended parallel to surfaces. Moreover, found that OH-terminated offer energetically close Fermi level. In particular,...

Recently, two-dimensional (2D) transition-metal carbides and nitrides, namely, MXenes have attracted a lot of attention for electronic energy storage applications. Due to large spin-orbit coupling the existence Dirac-like band at Fermi energy, it has been theoretically proposed that some will be topological insulators (TIs). Up now, all predicted TI belong carbides, whose atom is W, Mo, or Cr. Here, on basis first-principles ${\mathbb{Z}}_{2}$ index calculations, we demonstrate MXene...

After several ad hoc proposals of new 2-dimensional carbon structures, interest in their actual synthesis has begun to increase. One needs a clear orientation or criteria describe those structures an appropriate way. In the present paper, we propose systematic method for discovering stable crystals with sp2-bonding using advanced mathematical methods. There are two key ideas: geometric descriptions based on curvatures, symmetries, etc. and standard realization crystal lattices via harmonic...

The electronic properties of silicene zigzag nanoribbons with the presence perpendicular fields are studied by using first-principles calculations and generalized nearest neighboring approximation method. In contrast to planar graphene, in Si atoms not coplanar. As a result, applying two-dimensional sheet, on-site energy can be modulated band gap at Dirac point is open. buckled structure also creates height difference between two edges nanoribbons. We find that external modulate energies...

A tri-FeB₆sheet with a sandwich-like structure has been found to be novel stable two-dimensional allotrope which remarkable mechanical properties and tunable electronic properties.

An Mn stabilized boron sheet shows many unique properties, such as novel voltage-gated spin-filtering properties and oxidization induced half-metallicity.

Two-dimensional transition metal carbides and nitrides (named as MXenes) their functionalized ones exhibit various physical chemical characteristics.

Using density functional theory (DFT), we investigated the energy-storage capabilities of a two-dimensional TiSe monolayer for applications anode material Li/Na/K-ion batteries. The showed high thermodynamic stability at 800 K according to ab initio molecular dynamics (AIMD) simulation. ion-diffusion barrier was estimated be 0.29/0.36/0.33 eV Li/Na/K, respectively, indicating high-rate capacity this material. theoretical specific 422.63 mA h g-1 with an energy 1000.19, 802.30, and 802.41 mW...

Iron-based amorphous and nano-crystalline alloys have attracted a growing interest due to their potential in the application of magnetic coil production. However, fundamental understanding nano-crystallization mechanisms features structure are still lack knowledge. In present work, we performed ab initio molecular dynamics simulation clarify ionic electronic atomic scale, derive origin good property Fe85Si2B8P4Cu1 alloy. The gave direct evidence Cu-P bonding preference alloy, which may...

We have performed a set of first-principles simulations to consider the possible phase transitions in molecular crystals HCN under high pressure. Our calculations reveal several transition paths from orthorhombic tetragonal and then triclinic phases. The phases are second order, whereas those turn out be first-order type characterized by an abrupt decrease volume. show that, adjustment temperature pressure crystal, novel layered polymeric with insulating, semiconducting or metallic...

We study the graphene band-gap engineering by introducing different defects, namely defects breaking inversion symmetry and ones periodically patterning into superlattice such as regularly arranged antidots, etc. Comparing to primitive unit cell of graphene, pseudo-graphene superlattice, referred pristine supercell, modulates boundary condition accordingly. According energy band-folding picture, these superlattices can be categorized two groups on basis Dirac cone position. In some cases,...

Using both the first-principles method and tight-binding method, we have carried out detailed studies on electronic properties of silicene superlattices. According to band-folding picture, in hexagonal superlattice (M,N) when M N are integer multiples 3, simultaneous folding K K′ points Γ point results fourfold degeneracy. In orthogonal one [P,Q], degeneracy occurs if Q = 3q (q is an integer) satisfied. By introducing degenerate perturbation remove degeneracy, bandgap could be opened no...

Steps and their associated adatoms extensively exist play prominent roles in affecting surface properties of materials. Such impacts should be especially pronounced two-dimensional, atomically-thin membranes like graphene. However, how single adatom behaves at monatomic steps few-layer graphene is still illusive. Here, we report dynamics individual free-standing reduced under the electron beam radiations demonstrate prevalent existence even down to unexpectedly ultrasmall lateral size a...

We use density functional theory based nonequilibrium Green's function to self-consistently study the current through 1,4-benzenedithiol (BDT). The elastic and inelastic tunneling properties this Au–BDT–Au molecular junction are simulated, respectively. For case, it is found that tilted molecule can be modulated effectively by external gate field, which perpendicular phenyl ring. voltage amplification comes from modulation of interaction between electrodes molecules in junctions. electron...

Iron-based amorphous alloys have attracted a growing interest due to their potential in the application of magnetic coil production. However, magnetization this kind material is usually low lack long range ordering and high alloying element content. In paper, an Fe76B19P5 alloy was simulated with ab initio molecular dynamics based on previous simulation work Fe76Si9B10P5 exhibiting that electron absorbers such as B P can help enhance nearby Fe atoms. The present results show replacing Si...

In the work reported in this paper, ab initio molecular dynamics simulation was performed on Fe85Si2B9P4 amorphous alloy. Preferred atomic environment of elements analyzed with Voronoi polyhedrons. It showed that B and P atoms prefer less neighbors compared Fe Si, making them structurally incompatible rich structure repulsive to formation α-Fe. However, due low bonding energy caused by coordination number, diffusion rates were considerably large, resulting requirement fast annealing for...

MXenes, a family of two-dimensional transition metal carbides and nitrides, have various tunable physical chemical properties. Their diverse prospective applications in electronics energy storage devices triggered great interests science technology. MXenes can be functionalized by different surface terminations. Some O F monolayers been predicted to topological insulators (TIs). However, the reported OH TIs are very few their electronic structures need investigated more detail. It has...

Abstract The family of III–V element compounds (i.e., XY compounds; X = B, Al, Ga, In, or Tl; Y N, P, As, Sb) have been intensively investigated for several decades because their enormous applications many optoelectronic devices. Here, by employing first‐principles calculations, the electronic structures bulk haeckelite are examined. It is identified that InSb (TlN and TlP) Dirac semimetal (are strong topological insulators). other fifteen semiconducting. effect biaxial uniaxial tensile...

The bistable molecular switches have been studied theoretically based on the first-principles calculation. geometry structures of in this paper can be triggered between two symmetrical by using an external applied electric field. I-V characteristic curves different molecule configurations calculated, and distinguishability these indicates a switching behavior, performance which improved significantly some suitable donors acceptors.

By performing high-throughput first-principles calculations combined with a semiempirical van der Waals dispersion correction, we have screened 74 direct- and 185 indirect-gap two dimensional (2D) nonmagnetic semiconductors from near 1000 monolayers according to the criteria for energetic, thermodynamic, mechanical, dynamic thermal stabilities, conductivity type. We present calculated lattice constants, simulated scanning tunnel microscopy, formation energy, Young's modulus, Poisson's ratio,...