Variational transition state theory study of the reactions Li+HF and Li+HCl on the BO potential energy surfaces

Variational transition state theory is used to study the kinetics of the reactions Li+HF and Li+HCl on the BO potential energy surfaces, fitted to ab initio values by Lagana et al. The saddle point, the location of generalized transition state and other kinetic features on the bottleneck of the po- tential energy surface are obtained. We point out that the location of generalized transition state tends to the direction in which the two atoms with larger reduced mass separate off. It can be determined whether a potential energy surface is accurate or not by a fine analysis of its bottleneck region and a comparison of kinetic calculation with experimental result. This is helpful for building a more accurate potential energy surface.

Molecular Application of a State Specific Multi-Reference Brillouin-Wigner Perturbation Theory

The single reference second order Brillouin-Wigner perturbation theory recently developed, which eliminates its size-extensivity error, has been generalized to state-specific, multi-reference （SS-MR）, BWPT2 providing a size-extensive correction to the electron correlation problem for systems that demand the use of a multi-reference function. Illustrative numerical tests of the size-extensivity corrections are made for widely used molecules in their ground states, which are pronounced multi-reference characteristics. We have implemented two-reference and three-reference cases for CH2, BH and bond breaking process in the ground states of HF molecules. The results are compared with the rigorously size-extensive methods such as the M^ller-Plesset perturbation theory, i.e., MP2, full configuration interaction （Full-CI） and allied methods using the same basis sets.

The Rethinking of “State Shinto” in Japanese Academia After World War Ⅱ

The Shinto Directive,the official source of the term“State Shinto”,on the one hand defines the concept of“State Shinto”in a narrow sense,and on the other hand reveals its profound connotation and generalized extension.In 1945,after the Allied Forces issued the Shinto Directive,Japanese academia carried out in-depth research around“State Shinto”,and gradually formed the“two camps”consisting of scholars who advocated the theory of“State Shinto in a Broad Sense”and insisted on the theory of“State Shinto in a Narrow Sense”.In the process of promoting the democratic reform,the theory of“State Shinto in a Broad Sense”gradually developed into the general theory of“State Shinto”after the war;With the continuous advancement of empirical research,the“State Shinto in a Narrow Sense”gradually rose.While enriching the post-war research of“State Shinto”,it also provided a theoretical basis for historical revisionists to distort and cover up history.Finally,under the situation that the trend of Japanese political right deviation is increasingly intensified,the limitations of the“broad sense”and“narrow sense”camps are broken,and the study of“State Shinto”has entered a new stage.

Mechanism of K/Ni Etching for Biochar-H_(2)O Gasification

Biomass-H_(2)O gasification is a complex thermochemical reaction,including three processes of volatile removal:homogeneous/heterogeneous reforming,biochar gasification and etching.The rate-determining step is biochar-H_(2)O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni)in the zigzag biochar model.The calculation results show that the gasification of biochar-H_(2)O needs to go through four processes:dissociative adsorption of water,hydrogen transfer(hydrogen desorption,hydrogen atom transfer),carbon dissolution and CO desorption.The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step,which is reduced from 374.14 kJ/mol to 152.41 kJ/mol;the catalytic effect of Ni is mainly reflected in the carbon dissolution step,which is reduced from 122.34 kJ/mol to 84.8 kJ/mol.The existence of K causes the edge to have a stronger attraction to H and does not destroy theπbonds of biochar molecules.The destruction ofπbonds is mainly due to the role of H free radicals,while the destruction ofπbonds will lead to easier C-C bond rupture.Ni shows a strong attraction to O in OH,which forms strong Ni-O chemical bonds.Ni can also destroy the aromatic structure directly,making the gasification easier to happen.This study explored the catalytic mechanism of K/Ni on the biochar-H_(2)O gasification at the molecular level and looked forward to the potential synergy of K/Ni,laying a foundation for experimental research and catalyst design.

Temperature and hydrogen-like impurity effects on the excited state of the strong coupling bound polaron in a CsI quantum pseudodot

With hydrogen-like impurity（HLI） located in the center of Cs I quantum pseudodot（QPD） and by using the variational method of Pekar type（VMPT）, we investigate the first-excited state energy（FESE）, excitation energy and transition frequency of the strongly-coupled bound polaron in the present paper. Temperature effects on bound polaron properties are calculated by employing the quantum statistical theory（QST）. According to the present work＇s numerical results, the FESE, excitation energy and transition frequency decay（amplify） with raising temperature in the regime of lower（higher）temperature. They are decreasing functions of Coulomb impurity potential strength.

Unsteady-state Grinding Technology (III) Studies on the Surface Quality

In conventional grinding theory, the chief removed mode of ceramic coprocessor by diamond tools was brittle removal. In order to perform the plastic removal or ductility processing of engineering ceramics the high degree of accuracy and high rigidity grinner must be using micro grain size diamond grinding wheel to direct the processing of micron below rank depth to prevent form the occurring of the brittle processing zone. This will resulted in the high expense of grinding. The expense of grinding could even reach the 80% of the total manufacture cost of the ceramic part. Ultra-precision grinding for advanced ceramics has been achieved by the unsteady-state grinding technique. In this paper, we mainly deals with observing and analyzing the surface quality of the silicon nitride ground by pink fused alumina wheel in different grinding parameters. To optimize the grinding parameters in the process of the unsteady-state grinding, the experiments of X-ray diffraction, energy spectrum analysis, SEM observation and roughness measurement were performed. The results show that: 1. In the process of unsteady state grinding, high line speed (rotational speed) of the grind wheel can improve the roughness of the silicon nitride apparently. It was also evident that the larger the grain mesh size, the better the surface quality. 2. There exists an optimum combination of grinding conditions such as grinding wheel speed, rotational speed of the workpiece, feed rate between the grinding wheel and the workpiece, grinding times and cutting coolant. The surface quality of the silicon nitride can be up to the standard of mirror finishing. 3. By analyzing the finished surface with X-ray diffraction and energy spectrum, the existence of some new phases including titanium and alumina was proved. 4. By utilizing the unsteady state grinding technique, the surface roughness of Ra ≤ 0.030 μm can be achieved by grinding the silicon nitride with the pink fused alumina wheel in low cost. Based on the unsteady-state grinding technique, this paper put forward a new processing method which by utilizing aluminum oxide grinding wheel to perform burnishing process and impudent the low surface roughness processing of engineering ceramic, the Ra is about 0.01 μm. Furthermore, the working efficiency of this method is high, and the process cost is low, so it is a prospective processing method.

Unsteady-State Grinding Technology (II) Experimental Studies of Grinding Forces and Force Ratio

As is known to all, grinding force is one of the most important parameters to evaluate the whole process of grinding. Generally, the grinding force is resolved to three component forces, namely, normal grinding force F n, tangential grinding force F t and a component force acting along the direction of longitudinal feed which is usually neglected because of insignificance. The normal grinding force F n has influence upon surface deformation and roughness of workpiece, while the tangential grinding force F t mainly affect power consumption and service life of grinding wheel. In order to study deep into the process of the unsteady state grinding, we set up a measurement system to monitor the change of grinding force during the course of grinding and try to find some difference in the change of grinding force between the steady state grinding and unsteady state grinding. In the test, the normal and tangential grinding forces, F n and F t were measured by using a set of equipments including sensor, amplifier, oscilloscope and computer monitor. From the results, we can conclude that: 1) In the unsteady state grinding process, the values of the grinding forces are much lower than those of the steady state grinding process and the grinding force ratio showed a nonlinear fluctuation. 2) The tendency of the grinding forces in the process of the unsteady state grinding proved the existence of the cutting and micro-cutting actions. 3) Because the grinding force signals of the unsteady state grinding are much weaker than those of the steady state grinding, to obtain accurate value of the grinding forces, wave filtering is needed to be done. The whole process to filter the perturbation wave can be separated into three steps in order, changing the grinding force signals from analog signals into digital signals, FFT (fast Fourier transform) treatment to the digital signals, and IFFT(inversion fast Fourier transform) treatment to the digital signals after spectrum limitation.

Unsteady-State Grinding Technology (I) Theoretical Generalization and Research on Grinding Mechanism

In conventional grinding theory, it is obvious that there must be a very high hardness difference between grains of the grinding wheel and workpieces. The best grinding wheels are those giving the lowest "natural limiting surface roughness" while cutting at appreciable plunge velocities. With the development of new materials and new machining processes, conventional theories of grinding techniques are no longer suitable to explain many phenomena in the course of grinding procedures. In dealing with precision or ultra-precision grinding processes of advanced ceramics, many results of experiments and practical production have shown that grinding with super hard materials wheels is not the only method to machine advanced ceramics. This paper is intended to propose a new grinding theory named as unsteady-state grinding technique evolved from some phenomena that can not be explained by conventional grinding theory. Unsteady-state grinding technique means the technique which can make the surface roughness of the materials, especially hard and brittle, be up to the standard of ultra-precision machining by utilizing common wheels characteristic of inferior self-sharpening and wear-resistance. In the process of machining, the common wheel need to be redressed about 3～5 times and the time between two redressings is about 3～5 minutes. As a validation of the new grinding technology, experimental work was performed to prove the existence of the unsteady state in the process of ultra-precision grinding with common abrasive wheel-pink fused alumina wheel. From the results of the observation of the wheel topography, the whole grinding process in unsteady state was separated into three stages namely cutting by grains peaks, micro-cutting by micro edges of the broken grains and rubbing without material removal, which is different from conventional grinding theory. For the difference of hardness between grinding wheel and workpiece material is not so apparent, some people have doubts about whether the cutting especially micro-cutting actions exist in the process of unsteady state grinding. By utilizing the common abrasive wheel newly redressed to grind the finished surface of silicon nitride glut and comparing the finished surface with the damaged surface in SEM pattern and surface roughness, the existence of cutting and micro- cutting actions in the unsteady state grinding process was confirmed.

Density Functional Theory Study of C_2H_x(x=4～6) Adsorption on the Fe(110) Surface

The density functional theory（DFT） and self-consistent periodic calculation were used to investigate the C2Hx（x = 4～6） species adsorption on the Fe（110） surface. The adsorption energy and equilibrium geometry of the species C2Hx（x = 4～6） on four possible sites（top,hcp,SB and LB） on the Fe（110） surface were predicted and compared. Mulliken charges and density of states analysis of the most stable site have been discussed. It is found that the species of C2H6 and C2H5 are adsorbed strongly on the Fe（110） surface with calculated adsorption energy of -80.24 and -178.89 kJ·mol^-1 at the Fe-LB（long-bridge） ,respectively. However,the C2H4 is adsorbed strongly on the Fe（110） surface with calculated adsorption energies of -114.96 kJ·mol^-1 at the top. The results indicate that the charge transferring process can be completed by chemisorption between Fe（110） surface and the species. Moreover,the chemical bands can be formed by chemisorptions between the Fe（110） surface and the species,too.

Theoretical Study on the C-H Activation in Decarbonylation of Acetaldehyde by NiL_2(L=SO_3CH_3) Using Density Functional Theory

Density functional theory calculations were carried out to explore the potential energy surface（PES） associated with the gas-phase reaction of Ni L2（L=SO3CH3） with acetone. The geometries and energies of the reactants, intermediates, products and transition states of the triplet ground potential energy surfaces of [Ni, O, C2, H4] were obtained at the B3LYP/6-311＋＋G（d,p） levels in C,H,O atoms and B3LYP/ Lanl2 dz in Ni atom. It was found through our calculations that the decabonylation of acetaldehyde contains four steps including encounter complexation, C-C activation, aldehyde H-shift and nonreactive dissociation. The results revealed that C-C activation induced by Ni L2（L=SO3CH3） led to the decarbonylation of acetaldehyde.

Simple statistical model for predicting thermal atom diffusion on crystal surfaces

A simple model based on the statistics of single atoms is developed to predict the diffusion rate of thermal atoms in （or on） bulk materials without empirical parameters. Compared with vast classical molecular-dynamics simulations for predicting the self-diffusion rate of Pt, Cu, and Ar adatoms on crystal surfaces, the model is proved to be much more accurate than the Arrhenius law and the transition state theory. Applying this model, the theoretical predictions agree well with the experimental values in the presented paper about the self-diffusion of Pt （Cu） adatoms on the surfaces.

A statistical model for predicting thermal chemical reaction rate

A simple model based on the statistics of individual atoms [Europhys. Lett. 94 40002 （2011）] or molecules [Chin. Phys. Lett. 29 080504 （2012）] was used to predict chemical reaction rates without empirical parameters, and its physical basis was further investigated both theoretically and via MD simulations. The model was successfully applied to some reactions of extensive experimental data, showing that the model is significantly better than the conventional transition state theory. It is worth noting that the prediction of the model on ab initio level is much easier than the transition state theory or unimolecular RRKM theory.

Theoretical and Experimental Studies on the Reaction Mechanism of Cl_2 + I_2 = 2ICl

The gas phase reaction mechanism of Cl2 ＋ I2 = 2ICl has been theoretically investigated by DFF method at the B3LYP/3-21 G＊ level. Transition states of three reaction channels were consequently given. The results indicate that in the title reaction the least activation energy of bi-molecular reaction was smaller than the dissociation energies of I2 and Cl2, and thus the reaction mechanism was the course of molecule-molecule interaction at low reaction rate. If other factors such as illumination were taken into account, I2 could dissociate into I atoms and then react with Cl2, or Cl2 dissociates into CI atoms and reacts with I2. These were photochemical reactions with high reaction speed. The theoretical results were further validated with absorbance measurement at 516 nm.

Theory of ghost scattering with biphoton states

We show how quantum entangled biphoton states can be used to realize ghost scattering, a nonlocal scheme to obtain scattering information of an unknown object through the correlation measurement of the scattering photons in two different optical paths. We present a framework to describe the biphoton ghost scattering process from the T-matrix formula of the scattering theory. We find the scattering information of a test object can be retrieved from either the test arm or the reference arm. By adjusting the biphoton states, the ghost scattering patterns may be varied from the scattering pattern of the object in the test arm to the object in the reference arm.

First-Principles Study of the High-Temperature Behaviors of the Willemite-Ⅱ and Post-Phenacite Phases of Silicon Nitride

The structural and elastic properties of the recently-discovered wⅡ- and δ-Si3N4 are investigated through the plane-wave pseudo-potential method within ultrasoft pseudopotentials.The elastic constants show that wⅡ- and δ-Si3N4 are mechanically stable in the pressure ranges of 0-50 GPa and 40-50 GPa,respectively.The α→wⅡ phase transition can be observed at 18.6 GPa and 300 K.The β→δ phase transformation occurs at pressures of 29.6,32.1,35.9,39.6,41.8,and 44.1 GPa when the temperatures are100,200,300,400,500,and 600 K,respectively.The results show that the interactions among the N-2s,Si-3s,3p bands（lower valence band） and the Si-3p,N-2p bands（upper valence band） play an important role in the stabilities of the wⅡ and S phases.Moreover,several thermodynamic parameters（thermal expansion,free energy,bulk modulus and heat capacity） of δ-Si3N4 are also obtained.Some interesting features are found in these properties.δ-Si3N4 is predicted to be a negative thermal expansion material.The adiabatic bulk modulus decreases with applied pressure,but a majority of materials show the opposite trend.Further experimental investigations with higher precisions may be required to determine the fundamental properties of wⅡ- andδ-Si3N4.

On precise time integration method for non-classically damped MDOF systems

In the complex mode superposition method, the equations of motion for non-classically damped multiple-degree-of-freedom （MDOF） discrete systems can be transferred into a combination of some generalized SDOF complex oscillators. Based on the state space theory, a precise recurrence relationship for these complex oscillators is set up; then a delicate general solution of non-classically damped MDOF systems, completely in real value form, is presented in this paper. In the proposed method, no calculation of the matrix exponential function is needed and the algorithm is unconditionally stable. A numerical example is given to demonstrate the validity and efficiency of the proposed method.

Comparison of band structure and superconductivity in FeSe_(0.5)Te_(0.5) and FeS

The isovalent iron chalcogenides, FeSe0.5Te0.5 and FeS, share similar lattice structures but behave very differently in superconducting properties. We study the underlying mechanism theoretically. By first principle calculations and tight-binding fitting, we find the spectral weight of the dX2-Y2 orbital changes remarkably in these compounds. While there are both electron and hole pockets in FeSe0.5Te0.5 and FeS, a small hole pocket with a mainly dX2-Y2 character is absent in FeS. We find the spectral weights of dX2-Y2 orbital change remarkably, which contribute to electron and hole pockets in FeSe0.5Te0.5 but only to electron pockets in FeS. We then perform random-phase-approximation and unbiased singular-mode functional renormalization group calculations to investigate possible superconducting instabilities that may be triggered by electron-electron interactions on top of such bare band structures. For FeSe0.5Te0.5, we find a fully gapped s-wave pairing that can be associated with spin fluctuations connecting electron and hole pockets. For FeS, however, a nodal dxy （or dx2-y2 in an unfolded Broullin zone） is favorable and can be related to spin fluctuations connecting the electron pockets around the corner of the Brillouin zone. Apart from the difference in chacogenide elements, we propose the main source of the difference is from the dX2-Y2 orbital, which tunes the Fermi surface nesting vector and then influences the dominant pairing symmetry.

Study of magnetic and optical properties of Zn1-xTMxTe(TM = Mn,Fe,Co,Ni) diluted magnetic semiconductors：First principle approach

We present structural,magnetic and optical characteristics of Zn_（1-x）TM_xTe（TM = Mn,Fe,Co,Ni and x = 6.25%）,calculated through Wien2 k code,by using full potential linearized augmented plane wave（FP-LAPW） technique.The optimization of the crystal structures have been done to compare the ferromagnetic（FM） and antiferromagnetic（AFM） ground state energies,to elucidate the ferromagnetic phase stability,which further has been verified through the formation and cohesive energies.Moreover,the estimated Curie temperatures T_c have demonstrated above room temperature ferromagnetism（RTFM） in Zn_（1-x）TM_xTe（TM =Mn,Fe,Co,Ni and x= 6.25%）.The calculated electronic properties have depicted that Mn- and Co-doped ZnTe behave as ferromagnetic semiconductors,while half-metallic ferromagnetic behaviors are observed in Fe- and Ni-doped ZnTe.The presence of ferromagnetism is also demonstrated to be due to both the p-d and s-d hybridizations between the host lattice cations and TM impurities.The calculated band gaps and static real dielectric constants have been observed to vary according to Penn＇s model.The evaluated band gaps lie in near visible and ultraviolet regions,which make these materials suitable for various important device applications in optoelectronic and spintronic.

Theoretical Study on the Kinetics for the Reactions of Heptyl Radicals with Methanol

Ab initio study of the reactions ofn-heptyl radicals（1-C7H15, 2-C7H15, 3-C7H15, and 4-C7H15） with metha- nol was conducted over the temperature range of 300--1500 K. Transition states for the reaction channels producing CTH15OH, CH3, C7H15OCH3, H, C7H16, CH2OH and CH30 were identified and the geometries of all stationary points were calculated at BB1K/MG3S level of theory. The potential barrier heights of the corresponding transition states were predicted by the CBS-QB3//BB1K and G4//BB1K methods, indicating that the eight H-abstraction channels are more kinetically favorable than the channels where OH transfers from CH3OH to C7H15 and where the CTHIsOCH3＋H products are given. Tile rate constants of H-abstraction channels were calculated with TST and TST/Eck. Both the forward and reverse rate constants have positive temperature dependence and the ttmneling effect is only important at the temperature lower than 700 K. For the reactions of H-atom abstraction from methyl in CH3OH by n-heptyl, a reverse and the corresponding forward rate constant are roughly equal. For the reactions of H-atom abstraction from OH in CH3OH by n-heptyl, a reverse rate constant is larger by several orders of magnitude thin1 the corresponding forward one.

Unprecedented differences in the diamond nucleation density between carbon-and silicon-faces of 4H-silicon carbides

4H-silicon carbides deposited by diamond films have wide applications in many fields such as semiconductor heterojunction,heat sink and mechanical sealing.Nucleation plays a critical role in the deposition of the diamond film on 4H-silicon carbides.Nevertheless,as a typical polar material,the fundamental mechanism of diamond nucleation on different faces of 4H-silicon carbides has not been fully understood yet.In this contribution,nucleation of diamond was performed on the carbon-and silicon-faces of 4H-silicon carbides in a direct current chemical vapor deposition device.The nucleation density on the carbon-face is higher by 2-3 orders of magnitude compared to the silicon-face.Transmission electron microscopy verifies that there are high density diamond nuclei on the interface between the carbon-face and the diamond film,which is different from columnar diamond growth structure on the silicon-face.Transition state theory calculation reveals that the unprecedented distinction of the nucleation density between the carbon-face and the silicon-face is attributed to different desorption rates of the absorbed hydrocarbon radicals.In addition,kinetic model simulations demonstrate that it is more difficult to form CH2(s)-CH2(s)dimers on silicon-faces than carbon-faces,resulting in much lower nucleation densities on silicon-faces.