An Ab Initio Study of the Effect of Substituents on Protonation of the Carbonyl Group

1974 ◽  
Vol 52 (4) ◽  
pp. 546-554 ◽  
Author(s):  
A. C. Hopkinson ◽  
I. G. Csizmadia
Keyword(s):  
Binding Energy ◽  
Ab Initio ◽  
Potential Model ◽  
Negative Charge ◽  
Proton Affinities ◽  
The Core ◽  
Charge Potential ◽  
Neutral Compounds ◽  
Incoming Proton ◽  
Cis Isomer

Ab initio calculations have been performed on a series of molecules HCOX, where X=CH3, NH2, OH, F, H, and also on the corresponding oxygen protonated cations. Rotational studies show the incoming proton to be trans to the substituent X except in formyl fluoride, where internal hydrogen bonding stabilizes the cis isomer. The geometries of the fluoro- and amino-substituted cations have been optimized along with that of oxygen protonated ketene. Proton affinities are found to be very dependent on substituents with the order of basicity being [Formula: see text]an order which closely follows the negative charge on the oxygen. Plots of the computed charge on the carbon atoms against the core binding energy are different for the cations and neutral compounds but can be made to fall on the same line by correcting the binding energy using "the charge potential model" for the K-shell electron which is removed.

Multiscale Analysis of Silicon LPCVD Reactor

2005 ◽  
Author(s):  
Yukinori Sakiyama ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Multiscale Analysis ◽  
Potential Model ◽  
Research Work ◽  
Pair Potential ◽  
Dynamics Simulation ◽  
Molecular Orbital Calculations ◽  
Ongoing Research ◽  
Trajectory Calculations

We demonstrate the multiscale analysis of the transport phenomena in a low pressure reactor. In this method, the macroscopic phenomena such as the temperature and the density distribution are related to the microscopic electronic structure of atom/molecule. By connecting the different scales with physical models, the macroscopic properties are obtained starting from the first principle calculation without any empirical parameters. Here, we take the silicon epitaxial growth from a gas mixture of silane and hydrogen as an example. As the first step of this method, we calculated the intermolecular potential energy of SiH4/H2 using the ab initio molecular orbital calculations. Then, an analytical pair potential model was constructed to reproduce the potential energy surface obtained from the ab initio calculation. We have confirmed the validation of the potential model by comparing the experimental data of the transport properties with the molecular dynamics simulation using the potential model. Subsequently, the binary molecular collision models were constructed by the classical trajectory calculation using the potential model as the second step of the multiscale analysis. The trajectory calculations were conducted for the various combinations of the initial translational and the rotational energy. Through the statistical analysis of the trajectory calculations, the elastic/inelastic collision cross section and the scattering angle model were constructed. Finally, the direct simulation Monte Carlo simulation of flow field in a low parssure reactor was executed. The thin film thickness distribution was also investigated and discussed. This method was extended to analyze the surface reaction, which is an ongoing research work and only the current progress is reported here.

scholarly journals Simulations of Defect-Interface Interactions in GaN

2000 ◽  
Vol 5 (S1) ◽  
pp. 287-293
Author(s):  
J. A. Chisholm ◽  
P. D. Bristowe
Keyword(s):  
Electronic Structure ◽  
Binding Energy ◽  
Point Defects ◽  
Potential Model ◽  
Pair Potential ◽  
Planar Defects ◽  
Native Defects ◽  
Native Point Defects ◽  
Bulk Gan ◽  
Image Position

We report on the interaction of native point defects with commonly observed planar defects in GaN. Using a pair potential model we find a positive binding energy for all native defects to the three boundary structures investigated indicating a preference for native defects to form in these interfaces. The binding energy is highest for the Ga interstitial and lowest for vacancies. Interstitials, which are not thought to occur in significant concentrations in bulk GaN, should form in the (11 0) IDB and the (10 0) SMB and consequently alter the electronic structure of these boundaries.

Ab Initio Study of the Structure, Binding Energy, and Vibrations of the HOCl-H2O Complex

1995 ◽  
Vol 99 (7) ◽  
pp. 1919-1922 ◽  
Author(s):  
Theodore S. Dibble ◽  
Joseph S. Francisco
Keyword(s):  
Binding Energy ◽  
Ab Initio ◽  
Ab Initio Study

BINDING ENERGY OF HYDROGEN TO MIXED AND SCREW DISLOCATION

2005 ◽  
Vol 12 (02) ◽  
pp. 227-232 ◽  
Author(s):  
S. B. GESARI ◽  
B. L. IRIGOYEN ◽  
A. JUAN
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Binding Energy ◽  
Dominant Role ◽  
Dislocation Core ◽  
Electron Delocalization ◽  
The Core ◽  
Mixed Dislocation ◽  
Overlap Population ◽  
Bcc Iron

We have studied the effect of hydrogen on the cohesion of two types of dislocation in bcc iron at an atomistic level, using the atom superposition and electron delocalization molecular orbital (ASED-MO) method. The most stable positions for one hydrogen at each dislocation core were determined. It was found that the total energy of the cluster decreases when the hydrogen is located at the core. This effect is higher in a mixed dislocation in accordance with the experimental data. The computed results show that hydrogen is a strong embrittler and that a decrease in the Fe–Fe overlap population plays a dominant role in the decohesion of the crystal structure.

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