DFT study of optical properties of pure and doped graphene

Absorption and reflectivity of the lithium niobate surface masked with a graphene layerWe performed simulations of the interaction of a graphene layer with the surface of lithium niobate utilizing density functional theory and molecular dynamics at 300K and atmospheric pressure. We found that the graphene layer is physisorbed on the lithium niobate surface with an adsorption energy of -0.8205 eV/(carbonatom). Subsequently, the energy band structure, the optical absorption and reflectivity of the new system were calculated. We found important changes in these physical properties with respect to the corresponding ones of a graphene layer and of a lithium niobate crystal. © 2017 Author (s)

Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

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Absorption and reflectivity of the lithium niobate surface masked with a graphene layer

et al. 2017

“…Furthermore, refractive index of a structure can be calculated in terms of dielectric functions, i.e., n(ω) = ( ε 2 1 (ω) + ε 2 2 (ω) + ε 1 (ω)/2) 1/2 . For the pristine SnC, static refractive index, n(0) is found to be 1.65 which is higher than the refractive index of single-layer graphene (n(0) = 1.1 [61]). In the presence of applied strain, the tensile (compressive) strain increases (decreases) the refraction index as n(0) +2.5% = 1.75 and n(0) +5.0% = 1.93 (n(0) −2.5% = 1.58 and n(0) −5.0% = 1.52).…”

Section: Resultsmentioning

confidence: 77%

First principle and tight-binding study of strained SnC

Modarresi

Journal of Physics and Chemistry of Solids

et al. 2017

We study the electronic and optical properties of strained single-layer SnC in the density functional theory (DFT) and tightbinding models. We extract the hopping parameters tight-binding Hamiltonian for monolayer SnC by considering the DFT results as a reference point. We also examine the phonon spectra in the scheme of DFT, and analyze the bonding character by using Mulliken bond population. Moreover, we show that the band gap modulation and transition from indirect to direct band gap in the compressive strained SnC. The applied tensile strain reduces the band gap and eventually the semiconductor to semimetal transition occurs for 7.5% of tensile strain. In the framework of tight-binding model, the effect of spin-orbit coupling on energy spectrum are also discussed. We indicate that while tensile strain closes the band gap, spin-orbit gap is still present which is order of ∼ 40 meV at the Γ point. The substrate effect is modeled through a staggered sub-lattice potential in the tight-binding approximation. The optical properties of pristine and strained SnC are also examined in the DFT scheme. We present the modulation of real and imaginary parts of dielectric function under applied strain.

“…The static parallel refractive index n k ð0Þ ¼ 1:44 for monolayer blue phosphorus comparable with graphene (n k ð0Þ ¼ 1:12 and n ? ð0Þ ¼ 2:75) [46] and 2D-ZnS (n k ð0Þ ¼ 1:66) [47]. The main peak values of refractive index for monolayer, AA and AB stack bilayer blue phosphorus are 2.79 at 3.60 eV, 3.17 at 3.70 eV, and 3.75 at 3.60 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

Electronic and optical properties of bilayer blue phosphorus

Modarresi

Computational Materials Science

et al. 2016

a b s t r a c tWe investigate the electronic and optical properties of monolayer and stacking dependent bilayer blue phosphorus in the framework of density functional theory (DFT) and tight-binding approximations. We extract the hopping parameters of TB Hamiltonian for monolayer and bilayer blue phosphorus by using the DFT results. The variation of energy band gap with applied external electric field for two different stacks of bilayer blue phosphorus are also shown. We examine the linear response of the systems due to the external electromagnetic radiation in terms of the dielectric functions in the DFT theory. The relatively large electronic band gap and possibility of exfoliation form bulk structure due to weak interlayer coupling, make blue phosphorus an appropriate candidate for future electronic devices.