Quasiclassical trajectory theoretical study on the chemical stereodynamics of the O(~1D)+H_2→OH+H reaction and its isotopic variants (HD, D_2)

The quasiclassical trajectory （QCT） method is used to study stereodynamic information about the reaction O （1D）＋H2 --4OH＋H on the DK （Dobbyn and Knowles） （llA;） ab initio potential energy surface （PES）. A wide scale of collision energy （Ec） from 0.05 eV to 0.5 eV is considered in the dynamic calculations. To reveal the rovibrational excitation effect, calculations at a collision energy of 0.52 eV are carried out for the v = 0 - 5, j = 0 and v = 0, j -- 0 - 15 initial states. The two popularly used polarization-dependent differential cross sections （PDDCSs）, dtY0o/doh （0, 0） and dtra0/dtot（2, 0）, and two angular distributions, P（φr） and P（φr） are calculated to obtain an insight into the alignment and the orientation of the product molecules. From the calculations, we can obtain that the alignment of the OH product is weaker at high collision energy and becomes stronger with the increase of initial vibrational level, and it is almost insensitive to the initially rotational excitation. Influences of the mass values of isotopes （HD, D2） on the stereodynamics are also shown and discussed. Comparisons between available theoretical results and experimental results are made and discussed.

Quantum and quasiclassical dynamics of C(^(3)P)+H_(2)(^(1Σ_(g)^(+)))→H(^(2)S)+CH(^(2)Ⅱ)reaction:Coriolis coupling effects and stereodynamics

The dynamics of C+H_(2)→H+CH reaction is theoretically studied using the quasiclassical trajectory and quantum mechanical wave packet methods.The analysis of reaction probabilities,integral cross sections,and rate coefficients reveal the essential Coriolis coupling effects in the quantum mechanical wave packet calculations.The calculated polarizationdependent differential cross section,P(θ_(r))and P(Φ_(r))show that the j'of product rotational angular momentum is not only aligned along the y axis and the direction of the vector x+z,but also strongly oriented along the positive y axis.

Study on local mode vibrations of molecular vibrational excitation states in CH_4,SiH_4 and GeH_4 with quasiclassical trajectory method

By using the quasiclassical trajectory method,changes of normal and local mode vibrational excitation energies with time are investigated for XH_4 (X=C,Si,Ge) molecules.The results demonstrate that in a CH_4 molecule the coupling between C—H stretching vibration and H—C—H bending vibration is relative- ly large so that the energy transfer is fast;while in SiH_4 or GeH_4 molecules this coupling is relatively small and thus an obvious energy relaxation is observed.This implies that there exists approximate local mode vibrations for certain vibrational excitation states.

Quasiclassical trajectory study of the reaction NH(X^3∑^-)+H→N(~4S)+H_2

The dynamics of the NH + H→N+H2 reaction has been investigated by means of the 3D quasiclassical trajectory approach by using the LEPS potential energy surface.The calculated rate coefficient is in good agreement with the experimental value.The reaction was found to occur via a direct channel.The product H2 has a cold excitation of rotational state,but has a reverse distribution of the vibrational state with a peak at v=1.Based on the potential energy surface and the trajectory analysis,the reaction mechanism has been explained successfully.

Vector Correlations and Product Rotational Alignments of Reactions Ca+RBr→CaBr+R(R=CH_(3),C_(2) H_(5) and n-C_(3) H_(7))

The quasiclassical trajectory method is used to study the vector correlations of the reactions Ca＋RBr （R=CH3, C2H5 and n-C3H7Br） and the rotational alignment of product CaBr. The product rotational alignment parameters at different collision energies and the vector correlations between the reagent and product are numerically calculated. The vector correlations are described by using the angle distribution functions P（θr）, P（φr）, P（θr, φr） and the polarization-dependent differential cross sections （PDDCSs）. The peak values of P（θr） of the product CaBr from Ca＋CH3Br are larger than those from Ca＋C2H5Br and Ca＋n-C3H7Br. The peak of P（θr） at φr= 3π/2 is apparently stronger than that at φr= x/2 for the three reactions Ca＋RBr. The calculation results show that the rotational angular momentum of the product CaBr is not only aligned, but also oriented along the direction which is perpendicular to the scattering plane.The product CaBr molecules are strongly scattered forward. The orientation and alignment of the product angular momentum will affect the scattering direction of the product molecules to varying degrees.

THE KILLING FORMS AND DECOMPOSITION THEOREMS OF LIE SUPERTRIPLE SYSTEMS

In this article, the Killing form of a Lie supertriple system （LSTS） and that of its imbedding Lie superalgebra （LSA） are investigated, and a unique decomposition theorem for a quasiclassical LSTS with trivial center is established by means of the parallel decomposition theorem for a quasiclassical LSA.

The effect of the rotational excitation of NO on the stereodynamics for the reaction C(~3P)+NO(X^2Π)→CN(X^2Σ^+)+O(~3P)

The stereodynamic properties of the reaction C （^3P） ＋ NO （X2^П） →CN （X^2∑^＋） ＋ O （^3P） in different rotational states of reactant NO are studied theoretically by using the quasiclassical trajectory method on ^2A″ and ^2A′ potential energy surfaces （PESs） at a collision energy of 0.06 eV. The vector properties in different rotational states on the two surfaces are discussed in detail. The results indicate that the rotational excitation of NO has considerable influence on the stereodynamic property of the reaction occurring on the two surfaces. At the same time, the calculated polarization-dependent differential cross sections （PDDCSs） in different initial rotational states manifest that products are strongly polarized at three scattering angles.

Stereodynamics of O（^3P）＋H2 at Scattering Energies of 0.5, 0.75, and 1.0 eV

Quasiclassical trajectory calculation of the title reaction O（^3P）＋H2→OH＋H at three different scattering energies of 0.5, 0.75, and 1.0 eV on the lowest electronic potential energy surface 1^3A＂ has been done. Distribution P（θr） of polar angles between the relative velocityk of the reactant and rotational angular momentum vector j＇ of the product, distribution P（φr） of the azimuthal as well as dihedral angles correlating k-k＇-j＇, 3-dimensional distri-bution, and polarization-dependent differential cross sections （PDDCSs）dependent upon the scattering angle of the product molecule OH between the relative velocity k of the reactant and k＇ of the product at different scattering energies of 0.5, 0.75, and 1.0 eV are presented and discussed.

Stereodynamics study of the H'(~2S)+NH(X^3Σ^-)→N(~4S)+H_2 reaction

The stereodynamics and reaction mechanism of the H′（^2S） ＋ NH （X^3∑^-） → N（^4S） ＋ H2 reaction are thoroughly studied at collision energies in the 0.1 eV-1.0 eV range using the quasiclassical trajectory （QCT） on the ground 4A″ potential energy surface （PES）. The distributions of vector correlations between products and reagents P（φr）, P（φr） and P（φr,φr） are presented and discussed. The results indicate that product rotational angular momentum j′ is not only aligned, but also oriented along the direction perpendicular to the scattering plane; further, the product H2 presents different rotational polarization behaviors for different collision energies. Furthermore, four polarization-dependent differential cross sections （PDDCSs） of the product He are also calculated at different collision energies. The reaction mechanism is analyzed based on the stereodynamics properties. It is found that the abstraction mechanism is appropriate for the title reaction.

Theoretical study of stereodynamics for the reaction O(3P) ＋D2 (v=0, j=0) →OD＋D and isotope effect

Quasi-classical trajectory （QCT） calculations have been performed to study the product polarization behaviours in the reaction O（3p） ＋ D2 （v = 0, j = 0） → OD ＋ D. By running trajectories on the 3A′ and 3A″potential energy surfaces （PESs）, vector correlations such as the distributions of the polarization-dependent differential cross sections （PDDCSs）, the angular distributions of P（θr） and P（Фr） are presented. Isotope effect is discussed in this work by a comprehensive comparison with the reaction O（3p） ＋ H2 （v = 0, j = 0） → H ＋ H. Common characteristics as well as differences are discussed in product alignment and orientation for the two reactions. The isotope mass effect differs on the two potential energy surfaces： the isotope mass effect has stronger influence on P（θr） and PDDCSs of the 3A′ PES while the opposite on P（Фr） of the 3A′ potential energy surface.

Effects of Vibrational and Rotational Excitations on Dissociative Chemisorption Dynamics of N_(2) on Fe(111)

The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactivity on the Fe(111)surface,based on a recently developed six-dimensional potential energy surface.Six-dimensional quantum dynamics study was carried out to investi-gate the effect of vibrational excitation for incidence energy below 1.6 eV,due to sig-nificant quantum effects for this reaction.The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations.We found that raising the translational energy can enhance the dissociation probability to some extent,however,the vibrational excitation or rotational excitation can promote disso-ciation more efficiently than the same amount of translational energy.This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.

Stereodynamics study of the exchange reaction O(~3P)+CH_4 →H+OCH_3

A new London-Eyring-Polanyi-Sato potential energy surface is employed in this work to study the stereo properties of the O （^3p） ＋ CH4 → H ＋ OCH3 reaction in its rovibrationally ground state using the quasiclassical trajectory method （QCT）. Our calculations are performed at a range of collision energies, Ec = 1.5 eV^-3.5 eV, and the excitation function obtained by the QCT method accords well with the experimental data. The product rotational polarization is calculated, and the product shows a strong rotational polarization in the centre-of-mass coordinate system. The orientation of the product rotational angular momenta is sensitive to the increase in collision energy, and the alignment of the product rotational angular momenta shows some of the properties of the heavy heavy-light mass combination reactions. In the isotopic substituted reaction study, when the H atoms in methane are replaced by D atoms, the rotational polarization is obviously reduced. The polarization-dependent differential cross section is also studied by this QCT calculation to provide detailed information about the rotational alignment and orientation of the product.

The Wiedemann-Franz law in a normal metal-superconductor junction

In this paper the influence of superconducting correlations on the thermal and charge conductances in a normal metal-superconductor （NS） junction in the clean limit is studied theoretically. First we solve the quasiclassical Eilenberger equations, and using the obtained density of states we can acquire the thermal and electrical conductances for the NS junction. Then we compare the conductance in a normal region of an NS junction with that in a single layer of normal metal （N）. Moreover, we study the Wiedemann-Franz （WF） law for these two cases （iN and NS）. From our calculations we conclude that the behaviour of the NS junction does not conform to the WF law for all temperatures. The effect of the thickness of normal metal on the thermal conductivity is also theoretically investigated in the paper.

Stereodynamics in reaction O(~1D) + CH_4 →OH + CH_3

A theoretical study of the stereodynamics for reaction O(1D) + CH4→OH + CH3 has been carried out using the quasiclassical trajectory method(QCT) on a potential energy surface structured by Gonzalez et al. The integral cross sections(ICSs), differential cross sections(DCSs) and product rotational angular momentum polarization have been calculated. With the collision energy increasing, the ICS decreases. There is no threshold energy, because no barrier is found on the minimum energy path. The DCS results show that the backward and forward scatterings exist at the same time. With the collision energy increasing, the dominant rotation of the product changes from the right-handed direction to the left-handed direction in planes parallel to the scattering plane. In the isotopic effect study, the decrease of the mass factor weakens the polarization degree of the rotational angular momentum vectors of the products.

A Detailed Dynamics Study of the Reaction CH_4+Cl→HCl+CH_3

The detailed dynamics of the CH4+Cl→HCl+CH3 reaction has been investigated by means of the quasiclassical trajectory approach. The properties analyzed can be interpreted in terms of the main topological featUres of the potential energy surface used. on the basis of the theoretical results, two reaction channels are proposed: one is a direct channel and the other is a complex one.

Influence of Early-staged Energy Barrier on Stereodynamics of Reaction of LiH(v=0, j=0)＋H → Li ＋ H2

Theoretical studies of stereodynamics for reaction LiH（v=0, j=0）＋H → Li＋H2 have been carried out with quasiclassical trajectory method on two potential energy surfaces（PESs） structured as W-PES and P-PES. The main difference of the two PESs is at fixed angle of Li--H--H from 110° to 180°. In this angle range, there is an early- staged energy barrier on the P-PES, but there is no barrier on the W-PES. Some studies have been done to explore the influence of the early-staged energy barrier on this exothermic reaction. Integral cross sections, differential cross sec- tions and product rotational angular momentum of the reaction have been calculated. When Ec〈0.48 eV, the do- minant influence of barrier is to restrain reacting. However, when Ec〉0.48 eV, the dominant influence of barrier is to promote reacting. The angular distribution of the product H2 is extremely forward on both the PESs, because the life- time of most complexes is short. Totally, the lifetime on the P-PES is longer than that on W-PES for the existence of the barrier. With the collision energy increasing, on the both PESs, the distribution of the direction of the product H2 angular momentum changed, and there is a trend that peak at （90°,270°） gets weaker and peak at （90°,90°） gets stronger. The energy barrier weakens the degree of the rotation alignment of the H2.

Microdynamics study on reaction of atom H and radical NH(X^3Σ)

The dynamics of the H + NH→N + H2 reaction has been investigated by means of the 3-atom model quasiclassical trajectory approach. The LEPS potential energy surface is employed in the study, which is obtained from the ab initio results and has an early saddle point in the minimum energy path. The results indicate that the reaction product H2 is mainly scattered backward,and the reaction is found to occur via a direct channel. The product H2 is in a cold excitation of rotational state, but has a hot vibrational excitation. Based on the potential surface and the trajectory analysis, the reaction mechanism has been explained successfully.

THEORETICAL STUDY OF REACTION DYNAMICS OF H_(2)■H+H ON LITHIUM(100)SURFACE

A generalized LEPS potential energy surface of (H_2?H +H)/Li(100) plane systemwas constructed based on the ab initio SCF absorption and surface diffusion of a hydrogenatom on lithium(100) surface, and reaction kinetic behaviour of this system was investigatedby means of QCT method. It was shown from analysis of the feature of this potential energysurface that the activation energy of absorption of H_2 molecules on a lithium(100) planeis unnecessary and the dissociation of H_2 on the Li(100) plane relates closely to the adsorp-tion sites and adsorption fashions, and the horizontal manner of dissociation of H_2 is easierthan the standing one. And it was also shown from the analysis of various collision trajec-tories that the surface recombination probabilities of bi-hydrogen atoms at low covering arevery small, and that the surface dissociation probabilities of H_2 are controlled by its vibra-tional quantum number. The potential energy surface of gas-metal surface interaction systemconstructed here is convenient to study on reaction dynamics, and a good explanation forcrossed molecular beam experiments of surface activation of H_2 molecule can be offered byQCT kinetic calculations in this work.