Using first-principles plane wave calculations, we investigate two dimensional honeycomb structure of Group IV elements and their binary compounds, as well the compounds III-V elements. Based on optimization phonon mode determine that 22 different materials are stable correspond to local minima Born-Oppenheimer surface. We also find all containing one first row elements, B, C or N have planar structures. On other hand, in structures Si, Ge alternating atoms hexagons buckled, since stability...

The mechanical properties of monolayer GaS and GaSe crystals are investigated in terms their elastic constants: in-plane stiffness (C), Poisson ratio $(\ensuremath{\nu})$, ultimate strength $({\ensuremath{\sigma}}_{U})$ by means first-principles calculations. calculated constants compared with those graphene ${\mathrm{MoS}}_{2}$. Our results indicate that is a stiffer material than due to the more ionic character Ga-S bonds Ga-Se bonds. Although values very close each other, 0.26 0.25 for...

Motivated by a recent experiment that reported the successful synthesis of hexagonal $(h)$ AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013)], we investigate structural, electronic, and vibrational properties bulk, bilayer, monolayer structures $h$-AlN using first-principles calculations. We show phase bulk is stable direct-band-gap semiconductor. The calculated phonon spectrum displays rigid-layer shear mode at $274 {\text{cm}}^{\ensuremath{-}1}$ an ${E}_{g}$ $703...

Atomically thin nanoribbons (NRs) have been at the forefront of materials science and nanoelectronics in recent years. State-of-the-art research on nanoscale has revealed that electronic, magnetic, phononic, optical properties may differ dramatically when their one-dimensional forms are synthesized. The present article aims to review advances synthesis techniques theoretical studies NRs. structure is organized as follows: After a brief introduction low dimensional materials, we different...

Combining first-principles calculations with Landauer-B\"uttiker formalism, ballistic thermoelectric transport properties of semiconducting two-dimensional transition metal dichalcogenides (TMDs) and oxides (TMOs) (namely ${\mathrm{MX}}_{2}$ M = Cr, Mo, W, Ti, Zr, Hf; X O, S, Se, Te) are investigated in their 2H 1T phases. Having computed structural, as well electronic phononic for all structures, we report the ones. We find that phases four studied structures have very promising properties,...

First-principles calculations show that monatomic strings of carbon have high cohesive energy and axial strength, exhibit stability even at temperatures. Because their flexibility reactivity, chains are suitable for structural chemical functionalizations; they also form stable ring, helix, grid, network structures. Analysis electronic conductance various infinite, finite, doped string structures reveal fundamental technologically interesting features. Changes in doping geometry give rise to...

We report the results of a variational calculation energy and oscillator strength exciton ground state in spherical ionic quantum dot as function radius, assuming infinite potential barriers. The strong interaction with optical phonons is taken into account by using an effective between electron hole derived Pollmann B\"uttner. values ground-state energies calculated this are compared recent that treats confined interface independently, excellent agreement found. Comparisons two simpler...

In this study, we present a theoretical investigation of structural, electronic, and mechanical properties pentagonal monolayers carbon (p-graphene), boron nitride (p-B2N4 p-B4N2), silver azide (p-AgN3) by performing state-of-the-art first principles calculations. Our total energy calculations suggest feasible formation monolayer crystal structures composed entirely pentagons. addition, electronic band dispersion indicate that while p-graphene p-AgN3 are semiconductors with indirect...

The electronic properties, carrier mobility, and strain response of ${\mathrm{TiS}}_{3}$ nanoribbons (${\mathrm{TiS}}_{3}$ NRs) are investigated by first-principles calculations. We found that the properties NRs strongly depend on edge type (a or b). All a-${\mathrm{TiS}}_{3}$ metallic with a magnetic ground state, while b-${\mathrm{TiS}}_{3}$ direct band gap semiconductors. Interestingly, size position almost independent ribbon width. This feature promises constant in NR rough edges, where...

Carbon nanotubes, in which the two-dimensional hexagonal lattice of graphene is transformed into a quasi-one-dimensional by conserving local bond arrangement, provide several structural parameters for engineering novel physical properties suitable ultimate miniaturization.Recent interest nanoscience and nanotechnology has driven tremendous research activity carbon dealt with variety problems produced number new results.Most effort gone revealing various nanotubes functionalizing them...

Based on first-principles calculations we show that gold atoms can form both freestanding and tip-suspended chiral single-wall nanotubes composed of helical atomic strands. The freestanding, infinite (5,5) tube is found to be energetically the most favorable. While less favorable, experimentally observed (5,3) stretching between two tips corresponds a local minimum in string tension. Similarly, (4,3) predicted as favorable structure yet experimentally. Analysis band structure, charge...

Using ab initio density functional theory and quantum transport calculations based on nonequilibrium Green's function formalism we study structural, electronic, properties of hydrogen-terminated short graphene nanoribbons (graphene flakes) their functionalization with vanadium atoms. Rectangular flakes are stable, having geometric electronic structures quite similar to that extended nanoribbons. We show a spin-polarized current can be produced by pure, hydrogenated rectangular exploiting the...

We investigate quantum transport properties of triangular graphene flakes with zigzag edges by using first principles calculations. Triangular have large magnetic moments which vary the number hydrogen atoms terminating its edge and scale size. Electronic transmission current-voltage characteristics these flakes, when contacted metallic electrodes, reveal spin valve remarkable rectification features. The transition from ferromagnetic to antiferromagnetic state under bias voltage can,...

Motivated by the recent synthesis of layered hexagonal aluminum nitride ($h$-AlN), we investigate its layer- and strain-dependent electronic optical properties using first-principles methods. Monolayer $h$-AlN is a wide-gap semiconductor, which makes it interesting especially for usage in optoelectronic applications. The spectra 1-, 2-, 3-, 4-layered indicate that prominent absorption takes place outside visible-light regime. Within ultraviolet range, intensities increase with number layers,...

The structural, electronic, and magnetic properties of pristine, defective, oxidized monolayer TiS3 are investigated using first-principles calculations in the framework density functional theory. We found that a single layer is direct band gap semiconductor, bonding nature crystal fundamentally different from other transition metal chalcogenides. negatively charged surfaces makes this promising material for lubrication applications. formation energies possible vacancies, i.e. S, Ti, TiS,...

Employing density functional theory-based methods, we investigate monolayer and bilayer structures of hexagonal SnS$_{2}$, which is recently synthesized metal dichalcogenide. Comparison 1H 1T phases SnS$_{2}$ confirms the ground state to be phase. In its structure examine different stacking configurations two layers. It found that interlayer coupling in weaker than typical transition-metal dichalcogenides (TMDs) so alternative orders have similar structural parameters they are separated with...

Motivated by a recent experiment that reported the synthesis of new 2D material nitrogenated holey graphene (C$_2$N) [Mahmood \textit{et al., Nat. Comm.}, 2015, \textbf{6}, 6486], electronic, magnetic, and mechanical properties (C$_2$N), phosphorated (C$_2$P) arsenicated (C$_2$As) monolayer structures are investigated using first-principles calculations. Our total energy calculations indicate that, similar to C$_2$N monolayer, formation other two also energetically feasible. Calculated...

Nitrogen-doped graphene (N-graphene) was prepared by exposing the transferred to different substrates atomic nitrogen plasma.

By employing density functional theory-based methods, the structural, vibrational, electronic, and magnetic properties of monolayer α-RuCl₃ were investigated.

By performing density functional theory-based ab-initio calculations, Raman active phonon modes of novel single-layer two-dimensional (2D) materials and the effect in-plane biaxial strain on peak frequencies corresponding activities are calculated. Our findings confirm spectrum unstrained 2D crystals provide expected variations in under strain. The results summarized as follows; (i) soften (harden) applied tensile (compressive) strains, (ii) response to for out-of-plane vibrational have...

The effect of an applied electric field and the charging are investigated on magnetic anisotropy (MA) various stable two-dimensional (2D) crystals such as graphene, ${\mathrm{FeCl}}_{2}$, graphone, fluorographene, ${\mathrm{MoTe}}_{2}$ using first-principles calculations. We found that magnetocrystalline energy Co-on-graphene Os-doped-${\mathrm{MoTe}}_{2}$ systems change linearly with field, opening possibility tuning MA these compounds. In addition, can rotate easy-axis direction from...

Magnesium hydroxide $[\mathrm{Mg}{(\mathrm{OH})}_{2}]$ has a layered brucitelike structure in its bulk form and was recently isolated as new member of two-dimensional monolayer materials. We investigated the electronic optical properties crystals $\mathrm{Mg}{(\mathrm{OH})}_{2}$ ${\mathrm{WS}}_{2}$ their possible heterobilayer by means first-principles calculations. It found that both monolayers are direct-gap semiconductors these two typical van der Waals heterostructure with weak...

$\text{Ca}{(\text{OH})}_{2}$ crystals, well known as portlandite, are grown in layered form, and we found that they can be exfoliated on different substrates. We performed first principles calculations to investigate the structural, electronic, vibrational, mechanical properties of bulk, bilayer, monolayer structures this material. Different from other lamellar such graphite transition-metal dichalcogenides, intralayer bonding is mainly ionic, while interlayer interaction remains a weak...

We present a calculation of the variation binding energy heavy-hole exciton in highly ionic quantum well structure, as function width using variational approach. include effects exciton-phonon interaction and mismatches between particle masses dielectric constants barrier layers. The effect is described terms an effective potential electron hole, derived by Pollmann B\"uttner [J. H. B\"uttner, Phys. Rev. B 16, 4480 (1977)] exciton--bulk optical-phonon Hamiltonian. find that values energies...