scholarly journals DFT Study of the Electronic Structure of Cubic-SiC Nanopores with a C-Terminated Surface

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Calvino ◽  
A. Trejo ◽  
M. I. Iturrios ◽  
M. C. Crisóstomo ◽  
Eliel Carvajal ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Surface Passivation ◽  
Phase Changes ◽  
Surface Relaxation ◽  
Oh Radicals ◽  
Functional Theory ◽  
Band Gap Engineering ◽  
Chemical Surface

A study of the dependence of the electronic structure and energetic stability on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using density functional theory (DFT) and the supercell technique. The pores were modeled by removing atoms in the [001] direction to produce a surface chemistry composed of only carbon atoms (C-phase). Changes in the electronic states of the porous structures were studied by using different passivation schemes: one with hydrogen (H) atoms and the others gradually replacing pairs of H atoms with oxygen (O) atoms, fluorine (F) atoms, and hydroxide (OH) radicals. The results indicate that the band gap behavior of the C-phase pSiC depends on the number of passivation agents (other than H) per supercell. The band gap decreased with an increasing number of F, O, or OH radical groups. Furthermore, the influence of the passivation of the pSiC on its surface relaxation and the differences in such parameters as bond lengths, bond angles, and cell volume are compared between all surfaces. The results indicate the possibility of nanostructure band gap engineering based on SiC via surface passivation agents.

Band gap engineering of bulk and nanosheet SnO: an insight into the interlayer Sn–Sn lone pair interactions

2015 ◽  
Vol 17 (27) ◽  
pp. 17816-17820 ◽  
Author(s):  
Wei Zhou ◽  
Naoto Umezawa
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Lone Pair ◽  
Functional Theory ◽  
Band Gap Engineering ◽  
Lone Pair Interactions ◽  
Insight Into ◽  
Pair Interactions

The effects of interlayer lone-pair interactions on the electronic structure of SnO are explored using density-functional theory.

Atomic and Electronic Structure of LaAlO3 and LaAlO3:Mg from First-Principles Calculations

2009 ◽  
Vol 79-82 ◽  
pp. 1257-1260
Author(s):  
Li Guan ◽  
Li Tao Jin ◽  
Wei Zhang ◽  
Qiang Li ◽  
Jian Xin Guo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Lattice Structure ◽  
Cell Structure ◽  
Functional Theory ◽  
Super Cell ◽  
Direct Band ◽  
Experimental Values

In the present paper, the lattice structure, band structure and density of state of LaAlO3 and LaAlO3:Mg are calculated by first-principle method based on density functional theory. Firstly, we select the different cutoff energy and k-point grid in the calculations, and obtain the most stable geometry structure of single crystal LaAlO3. The calculated lattice parameters are a=b=5.441 Å, c=13.266 Å, which matches with experimental values. To deeply understand the electronic structure of LaAlO3, a 2×1×1 super-cell structure is established and the doping concentration of Mg at Al sites is 25%. From the band structure and density of states, it can be seen that LaAlO3 has a direct band gap Eg=3.6 eV. However, LaAlO3:Mg has a larger band gap Eg=3.89 eV and the Fermi level enters into the valence band, which indicates the holes are introduced. The calculated results show that the conductivity of LaAlO3:Mg is better than pure LaAlO3, which is in good agreement with experimental results.

First-principle study of the electronic structure and optical property of Nb-doped anatase TiO2

2014 ◽  
Vol 28 (17) ◽  
pp. 1450091
Author(s):  
Q. Y. Hou ◽  
Q. L. Liu ◽  
C. W. Zhao ◽  
Y. Zhang
Keyword(s):  
Electronic Structure ◽  
Optical Property ◽  
Band Gap ◽  
Absorption Edge ◽  
Short Wavelength ◽  
Density Functional ◽  
Functional Theory ◽  
Long Wavelength ◽  
The Density Functional Theory ◽  
The Stability

The absorption edge shifted to long wavelength direction and short wavelength direction of two opposite experimental conclusions have been reported, when the band-gap and absorption spectra of Nb -doped anatase TiO 2 were studied. In order to solve this contradiction, the electronic structure and the optical property of Nb heavy doped anatase TiO 2 have been studied by the first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory with +U method modification. The calculated results indicate that the higher the Nb -doping is, the higher the total energy is, the worse the stability is, the higher the formation energy is, the more difficult the doping is, the wider the optical band-gap is, the more obvious the absorption edge shifting to short wavelength direction is, the lower the absorptivity and the reflectivity is, which is in agreement with the experimental results. The reasonable interpretation of the contradiction has been reported in this paper, too.

Graphene sheet with periodic vacancy: A first principles study

2021 ◽  
Author(s):  
Deepti Maikhuri ◽  
Jaiparkash Jaiparkash ◽  
Haider Abbas
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Graphene Sheet ◽  
First Principles ◽  
Density Functional ◽  
Computational Analysis ◽  
Functional Theory ◽  
First Principles Study

Abstract We present a comprehensive first-principles study of the electronic structure of graphene sheet with periodic vacancy. We report the structural, electronic, and magnetic properties of the graphene sheet with periodic vacancy that possess 48 C & 28 H atoms. Computational analysis based on density functional theory predicts that the periodic vacancy can modulate the properties of graphene sheet. Results show that periodic vacancies lead to the manipulation of band gap & could be utilized to tailor the electronic properties of the sheet. Also, it is found that, the graphene sheet with periodic vacancy is non-magnetic in nature.

The External Crystal Structure and Electronic Structure are Simulated about Ge0.6Si0.4 Quantum Dots

2016 ◽  
Vol 852 ◽  
pp. 329-335
Author(s):  
Zhi Ke Gao ◽  
Chong Wang ◽  
Yu Yang ◽  
Jie Yang ◽  
Li Qiao Chen
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Band Gap ◽  
Silicon Germanium ◽  
Density Functional ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Band Shift ◽  
Functional Theory ◽  
Germanium Alloy

The alloy Ge0.6Si0.4 quantum dots were studied by using density functional theory. The change of the electronic structure of each crystal which grown in different simulation temperature condition were investigated by molecular dynamics simulation method. The results indicate that quantum dots of silicon germanium alloy occupy the narrow band gap of each crystal face from low to high temperature conditions. Since the atomic density and crystal configuration is different, the band gap values are relatively different. The mechanism of dielectric constant transition is well explained based on the inter-band and in-band shift of band structure.

The Electronic Structure of Ga-Doped Hydrogen-Passivated Germanene: First Principle Study

2020 ◽  
Vol 833 ◽  
pp. 157-161
Author(s):  
Mauludi Ariesto Pamungkas ◽  
Husain ◽  
Achmad Kafi Shobirin ◽  
Tri Sugiono ◽  
Masruroh Masruroh
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dft Calculation ◽  
First Principle ◽  
Hydrogen Passivation ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Hydrogenated Graphene

Germanene, which has the same structure as graphene, is an exciting novel 2D functionalized material that controls its band gap using functionalization. The effects of the Ga atom and hydrogen atoms on the structure of Ga-doped H-passivated germanene were investigated with a density functional theory (DFT) calculation. H-passivated germanene has a direct gap of 2.10 eV. Opening the band gap in the H-passivated germanene is due to transition from sp2 to sp3 orbital. Adsorption of the Ga adatom on H-site decrease the band gap to 1.38 eV. No interaction between Ga atoms and Hydrogen atoms was observed. Hence, their effects on the band structure of hydrogenated graphene were independent of each other. Our results suggest that hydrogen passivation combined with adsorption of the Ga adatoms could effectively control the band gap of germanene.

Sign in / Sign up

Export Citation Format

Share Document