THEORETICAL STUDY OF N2O ADSORPTION AND DECOMPOSITION AT REGULAR AND DEFECT SITES OF MgO (001) SURFACE

2003 ◽  
Vol 02 (01) ◽  
pp. 57-64 ◽  
Author(s):  
YI-JUN XU ◽  
JUN-QIAN LI ◽  
YONG-FAN ZHANG
Keyword(s):  
Oxygen Vacancy ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Defect Sites ◽  
Surface Oxygen Vacancy ◽  
F Center ◽  
Catalytic Reactivity ◽  
Vacancy Site ◽  
Mgo Surface

The adsorption of N 2 O at regular and defect sites of MgO (001) surface has been studied systematically using cluster models embedded in a large array of point charges by density functional method. The calculated results show that the MgO (001) surface with oxygen vacancies exhibits high catalytic reactivity toward N 2 O adsorptive-decomposition at variance with the regular MgO surface or the surface with magnesium vacancies. Much elongation of O–N bond of N 2 O after adsorption at oxygen vacancy site with O end of N 2 O down indicates that O–N bond has been broken with concurrent production of N 2, leaving a regular site instead of the original oxygen vacancy site (F center). Besides, the MgO (001) surface with magnesium vacancies hardly exhibits catalytic reactivity. It can be concluded that N 2 O dissociation is likely occurred at MgO (001) surface oxygen vacancy sites, which is consistent with the generally accepted viewpoint in the experiment.

S Adsorption at Regular and Defect Sites of the MgO (001) Surface: Cluster Model Study at DFT Level

2003 ◽  
Vol 10 (04) ◽  
pp. 691-695 ◽  
Author(s):  
Yi-Jun Xu ◽  
Jun-Qian Li ◽  
Yong-Fan Zhang
Keyword(s):  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Defect Site ◽  
Model Study ◽  
Defect Sites ◽  
Adsorbed Sulfur ◽  
Vacancy Site ◽  
Sulfur Adsorption ◽  
Regular Site

We have studied the adsorption of sulfur at regular and defect sites of the MgO (001) surface using cluster models embedded in a large array of point charges by the density functional method. The calculated results indicate that it is a chemical adsorption regarding sulfur at both the regular site and the defect site of the MgO (001) surface. Especially for sulfur adsorbed at different oxygen vacancy sites (F, F + and F 2+ centers) and different magnesium vacancy sites (V, V - and V 2- centers), it has very large adsorption energies, which reflects the fact that the MgO (001) surface with the vacancies is an excellent adsorbent for sulfur adsorption. Besides, we find that the adsorbed sulfur is almost inserted into the lattice for sulfur adsorbed at the magnesium vacancy site of the MgO (001) surface. The adsorption energy of sulfur on the MgO (001) surface with magnesium vacancies is much larger when compared to that on the MgO (001) surface with oxygen vacancies. At the same time, it is also found that the S behaves as an electron acceptor except that it is adsorbed at the magnesium vacancy site behaving as an electron donor.

Computer Simulation of an Synthetic Ultraviolet Absorbent in the Interface of DMB and DMF

2010 ◽  
Vol 146-147 ◽  
pp. 966-971
Author(s):  
Qi Hua Jiang ◽  
Hai Dong Zhang ◽  
Bin Xiang ◽  
Hai Yun He ◽  
Ping Deng
Keyword(s):  
Computer Simulation ◽  
Computer Simulations ◽  
Density Functional ◽  
Density Functional Method ◽  
Mean Field ◽  
Functional Method ◽  
Dynamic Density ◽  
Interface Phase ◽  
Simulation Results

This work studies the aggregation of an synthetic ultraviolet absorbent, named 2-hydroxy-4-perfluoroheptanoate-benzophenone (HPFHBP), in the interface between two solvents which can not completely dissolve each other. The aggregation is studied by computer simulations based on a dynamic density functional method and mean-field interactions, which are implemented in the MesoDyn module and Blend module of Material Studios. The simulation results show that the synthetic ultraviolet absorbent diffuse to the interface phase and the concentration in the interface phase is greater than it in the solvents phase.

A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method

2015 ◽  
Vol 242 ◽  
pp. 434-439 ◽  
Author(s):  
Vasilii E. Gusakov
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Localized States ◽  
Experimental Accuracy ◽  
Functional Theory ◽  
New Approach ◽  
The Density Functional Theory

Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.

scholarly journals Density-functional method for nonequilibrium electron transport

2002 ◽  
Vol 65 (16) ◽  
Author(s):  
Mads Brandbyge ◽  
José-Luis Mozos ◽  
Pablo Ordejón ◽  
Jeremy Taylor ◽  
Kurt Stokbro
Keyword(s):  
Electron Transport ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Nonequilibrium Electron
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