The Performance Research of Different Concentrations of Methyl Adsorption on Si (110) Surface

2014 ◽  
Vol 988 ◽  
pp. 121-124
Author(s):  
Zheng Xin Yan ◽  
Dong Zhi Yan ◽  
Qian Chen ◽  
An Gong ◽  
Qian Liao
Keyword(s):  
Electron Density ◽  
Adsorption Energy ◽  
First Principles ◽  
Structure Change ◽  
Density Difference ◽  
Energy Increase ◽  
Adsorption Models ◽  
Electron Density Difference ◽  
Adsorption Structure ◽  
Performance Research

First-principles method was carried out to investigate the methyl chemical adsorbing on Si (110) surface. To clarify the different concentrations of methyl on Si (110) surface, the mono-methyl, double-methyl, treble-methyl, and quadruple-methyl on the Si surface adsorption models were comparably investigated. Adsorption energy and methyl C-H bond structure change, density of states and electron density difference were used to analyze the structure change of adsorption models. The adsorption energy shows that Si surface top site has significant sensitivity to methyl, and the adsorption energy increase with the increasing methyl concentrations. The electron density difference data show charge transfer is obvious and electron cloud center tend to Si atom with Si-C bond formed. The PDOS of methyl reveals electron peaks move to the low direction about (5.5036, 5.7868, 5.8572, 5.8788eV) with the increasing concentrations of methyl. The data above exhibit that quadruple-methyl adsorption structure is more stable one. The conclusion can provide the insight for gas detection and sensors.

scholarly journals Structural inheritance and difference between Ti2AlC, Ti3AlC2 and Ti5Al2C3 under pressure from first principles

2017 ◽  
Vol 31 (03) ◽  
pp. 1750016 ◽  
Author(s):  
Qing-He Gao ◽  
An Du ◽  
Ze-Jin Yang
Keyword(s):  
Electron Density ◽  
Density Of States ◽  
First Principles ◽  
Lattice Parameter ◽  
Density Difference ◽  
Electron Density Difference ◽  
Structural Inheritance ◽  
Wide Pressure Range ◽  
Pauling Scale ◽  
End Members

The structural inheritance and difference between Ti2AlC, Ti3AlC2 and Ti5Al2C3 under pressure from first principles are studied. The results indicate that the lattice parameter a are almost the same within Ti2AlC, Ti3AlC2 and Ti5Al2C3, and the value of c in Ti5Al2C3 is the sum of Ti2AlC and Ti3AlC2 which is revealed by the covalently bonded chain in the electron density difference: Al–Ti–C–Ti–Al for Ti2AlC, Al–Ti2–C–Ti1–C–Ti2–Al for Ti3AlC2 and Al–Ti3–C2–Ti3–Al–Ti2–C1–Ti1–C1–Ti2–Al for Ti5Al2C3. The calculated axial compressibilities, volumetric shrinkage, elastic constant [Formula: see text], [Formula: see text] ratio, bulk modulus, shear modulus, and Young’s modulus of Ti5Al2C3 are within the range of the end members (Ti2AlC and Ti3AlC2) in a wide pressure range of 0–100 GPa. Only Ti2AlC is isotropic crystal at about 50 GPa within the Ti–Al–C compounds. All of the Ti 3d density of states curves of the three compounds move from lower energy to higher energy level with pressure increasing. The similarities of respective bond length, bond overlap population (Ti–C, Ti–Al and Ti–Ti), atom Mulliken charges under pressure as well as the electron density difference for the three compounds are discovered. Among the Ti–Al–C ternary compounds, Ti–Ti bond behaves least compressibility, whereas the Ti–Al bond is softer than that of Ti–C bonds, which can also been confirmed by the density of states and electron density difference. Bond overlap populations of Ti–Ti, Ti–C and Ti–Al indicate that the ionicity interaction becomes more and more stronger in the three structures as the pressure increasing. Mulliken charges of Ti1, Ti2, Ti3, C and Al are 0.65, 0.42, 0.39, −0.73, −0.04 at 0 GPa, respectively, which are consistent with the Pauling scale.

The Chemisorptions Mechanism Study of Methyl on Different Bonds in Porous Silicon

2013 ◽  
Vol 864-867 ◽  
pp. 399-403
Author(s):  
Dong Zhi Yan ◽  
Zheng Xin Yan ◽  
Tao Zhang ◽  
Hua Ping Yang ◽  
An Gong ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Charge Transfer ◽  
Electron Density ◽  
Low Energy ◽  
Density Difference ◽  
Density Of State ◽  
Mechanism Study ◽  
Electron Density Difference ◽  
Strength Difference ◽  
Model Structures

The absorbing kinetic process of methyl on Si (111) surface was comprehensively studied using the method of quantum mechanics. We optimized the model structures of radical CH3+, Si (111), and CH3+ on Si (111) to obtain a rational convergence for the present calculations. The electron density difference and density of states of each model were calculated by CASTEP. The electron density difference of CH3+ on Si (111) reveals that the charge transfer factor is difference for different absorption positions, which indicates that the bond strength difference. The density of state of model exhibits that the electronic peaks move to the low energy direction. However, the absorption on B (-8.57, -2.19, 0.91) position shows a higher electron shift which evidences that it is the appreciating absorption position.

Rechnerische Simulation eines ein-dimensionalen Fehlordnungsmodells für K0,5V2O5

1999 ◽  
Vol 214 (2) ◽  
Author(s):  
H. Katzke ◽  
K. Kato
Keyword(s):  
Electron Density ◽  
Computer Simulations ◽  
Volume Ratio ◽  
Density Difference ◽  
Electron Density Difference ◽  
One Dimensional ◽  
Difference Map

AbstractA one-dimensional disorder model has been proposed for the structure of the so-calledComputer simulations showed, that the structure published by these authors can be explained by a model in which the layer sequences of the orthorhombic and the monoclinic structures randomly appear in a volume ratio of about 7 to 3. The trigonal-prismatically six-fold coordinated K position has been revealed to be a false maximum in the electron-density difference map. The orthorhombic (

scholarly journals Formaldehyde Molecules Adsorption on Zn Doped Monolayer MoS2: A First-Principles Calculation

2021 ◽  
Vol 8 ◽  
Author(s):  
Huili Li ◽  
Ling Fu ◽  
Chaozheng He ◽  
Jinrong Huo ◽  
Houyong Yang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
Chemical Properties ◽  
Adsorption Behavior ◽  
First Principles Calculation ◽  
Impurity States ◽  
Adsorption Structure ◽  
Small Clusters

Based on the first principles of density functional theory, the adsorption behavior of H2CO on original monolayer MoS2 and Zn doped monolayer MoS2 was studied. The results show that the adsorption of H2CO on the original monolayer MoS2 is very weak, and the electronic structure of the substrate changes little after adsorption. A new kind of surface single cluster catalyst was formed after Zn doped monolayer MoS2, where the ZnMo3 small clusters made the surface have high selectivity. The adsorption behavior of H2CO on Zn doped monolayer MoS2 can be divided into two situations. When the H-end of H2CO molecule in the adsorption structure is downward, the adsorption energy is only 0.11 and 0.15 eV and the electronic structure of adsorbed substrate changes smaller. When the O-end of H2CO molecule is downward, the interaction between H2CO and the doped MoS2 is strong leading to the chemical adsorption with the adsorption energy of 0.80 and 0.98 eV. For the O-end-down structure, the adsorption obviously introduces new impurity states into the band gap or results in the redistribution of the original impurity states. All of these may lead to the change of the chemical properties of the doped MoS2 monolayer, which can be used to detect the adsorbed H2CO molecules. The results show that the introduction of appropriate dopant may be a feasible method to improve the performance of MoS2 gas sensor.

Analysis of the Effect of Nitrogen on Cold Shortness Behavior of Steel with the Electron Structure Parameters of Phase Interface

2011 ◽  
Vol 299-300 ◽  
pp. 151-154
Author(s):  
Gui Li Yin ◽  
Deng Li Yi ◽  
Cheng Lin
Keyword(s):  
Electron Density ◽  
Order Approximation ◽  
Phase Interface ◽  
Electron Structure ◽  
Density Difference ◽  
Strengthening Effect ◽  
Electron Density Difference ◽  
Empirical Electron Theory ◽  
Cold Shortness ◽  
First Order Approximation

Based on the empirical electron theory of solids and molecules (EET), the phase interface electron structure of Fe4N/a-Fe、AlN/γ-Fe、AlN/γ-Fe-C(Al) are calculated, and the reasons that the cold shortness is resulted from nitrogen as well as the add of Al element is helpful to the removal of cold shortness are analyzed with the use of the interface conjunction factors such as,σ and. The calculated results are as follows. The discontinuous electron density difference of phase interface Fe4N/a-Fe under the first order approximation results in the remarkable strengthening effect as well as the significant decrease in toughness and ductility, demonstrating the reason that nitrogen can cause cold shortness; as the electron density difference on AlN/γ-Fe、AlN/γ-Fe-C(Al) phase interface is very large and the continuous number of the phase interface is very small, the add of Al can hinder the growth of grain, as a result, the austenite grain is significantly refined and the removal of cold shortness caused by Fe4N can be achieved.

STUDY ON THE RELATIONSHIP BETWEEN VALENCE ELECTRON STRUCTURE AND COATING ORIENTED GROWTH

2015 ◽  
Vol 22 (03) ◽  
pp. 1550039
Author(s):  
SHUYONG TAN ◽  
XUHAI ZHANG ◽  
RUI ZHEN ◽  
LEI ZHANG ◽  
ZENG TIAN ◽  
...  
Keyword(s):  
Electron Density ◽  
Valence Electron ◽  
Preferred Orientation ◽  
Density Difference ◽  
Crystal Face ◽  
Oriented Growth ◽  
Valence Electron Structure ◽  
Electron Density Difference ◽  
Fine Grain ◽  
Calculation Results

The coating oriented growth has attracted great attention because of its effect on coating properties. In this paper, the valence electron structures of TiN and Ni were calculated with the empirical electron theory (EET) in solid and molecules for investigating preferred orientation of nitride coatings containing Ni . The calculation results show that Ni (111), CrN (100) and TiN (100) are the maximum crystal-face electron density, respectively. In CrN (or TiN ) coatings, if Ni does not form a single nickel phase, CrN (100) (or TiN (100)) preferred orientation appears easily due to its high crystal-face electron density. When Ni exists as a single phase, CrN (100)/ Ni (111) (or TiN (100)/ Ni (111)) with the minimum crystal-face electron density difference is the most likely to appear in the coatings. Furthermore, high crystal-face electron density difference usually implies fine grain microstructure. The calculation results are consistent with the experimental results.

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