scholarly journals Effect of Point Defects on Electronic Properties and Structure of Talc (001) Surface by First Principles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 69
Author(s):  
Xindi Ma ◽  
Huicong Du ◽  
Ping Lan ◽  
Jianhua Chen ◽  
Lihong Lan
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Surface States ◽  
State Density ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Impurity Atoms ◽  
Electron State Density ◽  
Calculation Results ◽  
Impurity Defects

The surface structure and electronic properties of Mg vacancy defects on talc (001) and impurity defects with Fe, Mn, Ni, Al, and Ca replacing Mg atoms were calculated by using density functional theory. The calculation results show that the order of impurity substitution energy is Mn < Ni < Al < Ca < Fe. This indicates that Fe impurity defects are most easily formed in talc crystals. The covalent bonding between Si atoms and reactive oxygen atoms adjacent to impurity atoms is weakened and the ionic property is enhanced. The addition of Fe, Mn, and Ni atoms makes the surface of talc change from an insulator to a semiconductor and enhances its electrical conductivity. The analysis of electron state density shows that surface states composed of impurity atoms 4S orbital appear near the Fermi level.

The Effect of Impurity Atoms on the Structural and Electronic Properties of Au3 Clusters

2012 ◽  
Vol 507 ◽  
pp. 21-24
Author(s):  
Dong Mei Li ◽  
Zhi Hua Xiong ◽  
Qi Xin Wan
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Molecular Orbital ◽  
Density Functional ◽  
The Other ◽  
Functional Theory ◽  
Impurity Atoms ◽  
Highest Occupied Molecular Orbital ◽  
Structural And Electronic Properties ◽  
Bonding Properties

With density functional theory, the structural and electronic properties of Au3 and Au2M (M=Ag, Cu, Pd and Pt) clusters have been studied. The structural results indicate that by substituting one Au atom with M atom, the corresponding geometries are changed slightly. To investigate the electronic properties, bonding properties and highest occupied molecular orbital (HOMO) were observed. It is found that most trends in Au2Pd and Au2Pt are similar and it also happens in the other two doped clusters. In addition, the calculated mulliken overlap populations suggest that doping modify the localized electron between Au and Au atom. It is also found that the contributions from various atoms on HOMO and energies of HOMO are changed. These may make difference in the adsorption of clusters.

ELECTRONIC STRUCTURES AND THE STABILITY OF MgO SURFACE: DENSITY FUNCTIONAL STUDY

2015 ◽  
Vol 22 (03) ◽  
pp. 1550037 ◽  
Author(s):  
DIAN-NA ZHANG ◽  
LI ZHAO ◽  
JIA-FU WANG ◽  
YAN-LI LI
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Chemical Potential ◽  
Surface States ◽  
Functional Study ◽  
Functional Theory ◽  
Calculation Results ◽  
The Stability ◽  
Mgo Surface

The electronic structures and the stability of the low-index surface (001), (011) and (111) for MgO were investigated by first-principles method based on density functional theory (DFT). We analyzed the stability of the MgO slab in equilibrium with an arbitrary oxygen environment. The density of states (DOS) and the band structures of MgO slabs were calculated and compared with those of the bulk MgO . Our calculation results reveal that the stabilities of the surface vary with the change of O chemical potential. In addition, the (001) and (011) surfaces are semiconductors, which are similar to that of the bulk MgO . However, the MgO (111) surface exhibits metallic property due to the effect of the surface states, which is different from that of the bulk MgO .

First-Principle Study of Structural and Electronic Properties of Ti-Doped SnO2

2013 ◽  
Vol 634-638 ◽  
pp. 2545-2549 ◽  
Author(s):  
Jing Kai Yang ◽  
Hong Li Zhao ◽  
Yan Zhu ◽  
Li Ping Zhao ◽  
Jian Li
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
First Principle ◽  
Generalized Gradient ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Calculation Results

The structural and electronic properties of Ti-doped SnO2with 6.25 at.% are investigated with the first principle calculations based on the density functional theory within the generalized gradient approximation. The calculation results indicate that the crystal structure of Sn0.9375Ti0.0625O2possesses a smaller volume; the bond length of Ti-O is shorter than that of Sn-O; the relative angle θ change value of Sn-O-Sn→Ti-O-Ti is about 1.07%. Ti-O bond possesses more covalent ingredient and stronger bond energy than Sn-O bond. After the replacement of one Ti atom, O atom bonded with Ti atom possessed fewer electrons, the ratio of charges possessed by Ti atom and O atom dose not agree with the stoichiometry of compound, create more holes at the top of VB of Sn0.9375Ti0.0625O2, and lead to the increase of the conductivity.

Thin Film Electronic Properties of Ternary Topological Insulator

2012 ◽  
Vol 1393 ◽  
Author(s):  
Jiwon Chang ◽  
Leonard F. Register ◽  
Sanjay K. Banerjee ◽  
Bhagawan Sahu
Keyword(s):  
Thin Film ◽  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Surface States ◽  
Bulk Region ◽  
Dirac Cone ◽  
Functional Theory ◽  
Ternary Compounds ◽  
Critical Film Thickness

ABSTRACTUsing an ab initio density functional theory (DFT), we study thin film electronic properties of topological insulators (TIs) based on ternary compounds of Tl (thallium) and Bi (bismuth). We consider TlBiX2 (X=Se, Te) and Bi2X2Y (X, Y=Se, Te) compounds. Here we discuss the nature of surface states, their locations in the Brillouin Zone (BZ) and their interactions within the bulk region. Our calculations suggest a critical film thickness to maintain the Dirac cone which is smaller than that in binary Bi-based compounds. Atomic relaxations are found to affect the Dirac cone in some of these compounds. We discuss the penetration depth of surface states into the bulk region.

scholarly journals Effect of Nitrogen Impurity on Electronic Properties of Boron Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Sandeep Kumar Jain ◽  
Pankaj Srivastava
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Nitrogen Doping ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Functional Theory ◽  
Impurity Atoms ◽  
Nitrogen Impurity ◽  
First Time

For the first time we present electronic band structure and density of states for nitrogen doped hexagonal ultrathin boron nanotubes in the framework of density functional theory. The considered models of nanotubes below 5 Å diameter are armchair (3,3), zigzag (5,0), and chiral (4,2). The impurity chosen for the study is nitrogen and concentration of impurity atoms is limited to two. The study reveals that (3,3) BNT retains its metallic nature after nitrogen doping. However, metallicity gets increased which is attributed by the excess electrons of nitrogen. Further, it also brings out that (5,0) BNT which is originally metal transforms into semiconductor after nitrogen interaction and the band gap at G point increases with the impurity. Moreover, the band gap of (4,2) BNT reduces significantly and turns into semimetal for nitrogen doping. Thus, the nitrogen impurity has the predominant effect on the electronic properties of BNTs and therefore can be regarded as suitable candidates for nanoelectronic and field emission devices.

scholarly journals Defect Processes in Halogen Doped SnO2

2021 ◽  
Vol 11 (2) ◽  
pp. 551
Author(s):  
Petros-Panagis Filippatos ◽  
Nikolaos Kelaidis ◽  
Maria Vasilopoulou ◽  
Dimitris Davazoglou ◽  
Alexander Chroneos
Keyword(s):  
Electronic Properties ◽  
Tin Oxide ◽  
Density Functional ◽  
Structural Changes ◽  
High Dielectric Constant ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Optical And Electronic Properties ◽  
High Dielectric ◽  
Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

scholarly journals Magnetic crystalline-symmetry-protected axion electrodynamics and field-tunable unpinned Dirac cones in EuIn2As2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. X. M. Riberolles ◽  
T. V. Trevisan ◽  
B. Kuthanazhi ◽  
T. W. Heitmann ◽  
F. Ye ◽  
...  
Keyword(s):  
Density Functional ◽  
Surface States ◽  
Antiferromagnetic Order ◽  
Functional Theory ◽  
Magnetic Symmetry ◽  
Integer Quantum ◽  
Symmetry Protected ◽  
Topological Crystalline Insulator ◽  
Low Symmetry ◽  
Crystalline Symmetry

AbstractKnowledge of magnetic symmetry is vital for exploiting nontrivial surface states of magnetic topological materials. EuIn2As2 is an excellent example, as it is predicted to have collinear antiferromagnetic order where the magnetic moment direction determines either a topological-crystalline-insulator phase supporting axion electrodynamics or a higher-order-topological-insulator phase with chiral hinge states. Here, we use neutron diffraction, symmetry analysis, and density functional theory results to demonstrate that EuIn2As2 actually exhibits low-symmetry helical antiferromagnetic order which makes it a stoichiometric magnetic topological-crystalline axion insulator protected by the combination of a 180∘ rotation and time-reversal symmetries: $${C}_{2}\times {\mathcal{T}}={2}^{\prime}$$ C 2 × T = 2 ′ . Surfaces protected by $${2}^{\prime}$$ 2 ′ are expected to have an exotic gapless Dirac cone which is unpinned to specific crystal momenta. All other surfaces have gapped Dirac cones and exhibit half-integer quantum anomalous Hall conductivity. We predict that the direction of a modest applied magnetic field of μ0H ≈ 1 to 2 T can tune between gapless and gapped surface states.

Geometric, electronic properties of Au$_l$Pt$_m$ ($l$+$m$$\leqslant$10) clusters: A first-principles study

2021 ◽  
Author(s):  
Wei-Feng Xie ◽  
Hao-Ran Zhu ◽  
Shi-Hao Wei
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Inverse Design ◽  
Functional Theory ◽  
First Principles Study

The structural evolutions and electronic properties of Au$_l$Pt$_m$ ($l$+$m$$\leqslant$10) clusters are investigated by using the first$-$principles methods based on density functional theory (DFT). We use Inverse design of materials by...

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