• Abstract

• Abstract

By using multi-reference configuration interaction method and large allelectron basis sets aug-cc-pwCV5Z, we have calculated the dense potential energy curves (PECs) of 1¹Σ^+, 1³Σ^+, 1¹Π, and 1³Π states of LiBe^+ molecule. Based on the obtained PECs, the analytical potential energy functions (APEF) have been constructed with a Morse long-range potential function and nonlinear least squares method. The rotational and vibrational energy levels of the four states are determined by solving Schrödinger equation of nuclear movement with the APEFs. The spectroscopic parameters are deduced with the obtained rotational and vibrational energy levels.

• Abstract

The stereodynamics of the atom-molecule reaction N(^4S)+O_2(X^3Σ^-_g) → O(^3Π) +NO(X^2Π) has been studied using quasi-classical trajectory method with the lowest 2A' potential energy surfaces (PESs) given by Sayós et al. [R. Sayós, C. Oliva, M. González, J. Chem. Phys. 117 (2002) 670]. Four generalized polarization-dependent differential cross-sections [(2π/σ) (dσ_{00}/dω_t), (2π/σ)(dσ_{20}/dω_t), (2π/σ)(dσ_{22+}/dω_t), (2π/σ)(dσ_{21-}/dω_t)] and distributions P(θ_r), P(Φ_r) were calculated. The effects of the different initial rotational and vibrational states were analyzed. It found that the degree of the forward scatting and the product polarizations show obviously change along with the initial vibration number, which leads to the increase of alignment and decrease orientation of product rotational angular momentum j'. Although the influence of the initial rotational excitation effect on the aligned and oriented distribution of product is not stronger than that of the initial vibration excitation effect, the initial rotational excitation makes the alignment of the product rotational angular momentum small change in a certain range. Moreover, the P(θ_r) distribution and P(Φ_r) distribution change noticeably by varying the initial vibration number.

• Abstract

TExcited state reaction coordinates and the consequent energy profiles of a new Schiff base, N-salicilydenemethylfurylamine (SMFA), have been investigated with the MP2 and CASSCF method. The potential energy profiles of the ground and the lowest excited singlet state are calculated. The excited state potential energy profile shows a small barrier in the LIIC pathway of dissociation along the O-H stretching coordinate. This work suggests that there are two pathways in the photochemical reaction of SMFA. In one pathway, the photochemical product is the enol-type minimum. In the other pathway, the ESIPT reaction is observed and a excited state stationary structure is reached. The trans-keto and cis-keto type structures will be obtained from photoexcitation of the enol isomer. Two conical intersections between the ground and excited states act as the gates for nonadiabatic decay to the ground state.

• Abstract

The equilibrium structure, spectroscopy constants and anharmonic force field of PO^-_2 anion have been investigated at MP2, B3LYP, B3P86, B3PW91 methods employing three basis sets, 6-311++G(2d,2p), 6-311++G(3df,3pd) and cc-pVQZ, respectively. The computed geometries, rotational constants, vibration-rotation interaction constants, quartic centrifugal distortion constants, and coriolis coupling constants of PO^-_2 are comparedwith the available experimental or theoretical data. The fundamental frequencies, rotational constants of ground state, sextic centrifugal distortion constants, cubic and quartic force constants of PO^-_2 are firstly predicted. The calculated results show that the B3P86/6-311++G(3df, 3pd) results are in excellent agreement with experiment and represent a substantial improvement over the results obtained from MP2. The other DFTmethods are also advisable choices to study the anharmonic force field of PO^-_2. The predicted spectroscopic constants may provide the useful data for the experiment studies of the corresponding spectroscopic constants of PO^-_2.

• Abstract

The molecular geometries, spectroscopy constants, and anharmonic force field of hypochlorous acid have been calculated at B3PW91, MP2, CCSD(T) levels of theory employing three basis sets, 6-311g(3df,2p), 6-311g(3df,3pd) and cc-pVQZ, respectively. The equilibrium structures, rotational constants, anharmonicity constants, vibration-rotation interaction constants, quartic and sextic centrifugal distortion constants are compared with the available experimental data. Coriolis coupling constants are also calculated here. The partial spectroscopy constants show that the MP2 represent an improvement over the results obtained from B3PW91. The CCSD(T) method is also a good choice to study the anharmonic force field of this molecule.

• Abstract

The additivity rule for electron scattering from molecule has been revised by considering the difference between the free atom and the corresponding bound atom in the molecule. The total cross sections for electron scattering from plasma etching molecules CF_4, C_2F_4, C_2F_6 and C_3F_8 have been calculated in the energy range from 100 eV to 5000 eV with the revised additivity rule. The present calculations are compared with the original additivity rule results and the existing experimental data. A better agreement between the present results and the experimental data is obtained.

• Abstract

The interference effect in the photdetachment of a diatomic molecular anion is investigated theoretically for different molecular orientation by using the twocenter model. An analytic formula is presented for the photodetached electron flux distribution at a given observation plane. Taking H^-_2 as an example, we calculate the electron flux distribution and photodetachment cross section for arbitrary molecular orientation. The results show that the molecular orientation has great influence on the photodetachment of the diatomic molecular anion. At certain molecular orientation, the interference in the electron flux distribution is totally constructive; while at some other orientations, the interference is destructive. For molecular orientation along the laser light polarization, the oscillation amplitude in the photodetachment cross section is the largest; however, for the molecular orientation perpendicular to the laser light polarization, no oscillation appears in the cross section. Our studies suggest that we can control the photodetachment process of the molecular negative ion by changing the molecular orientation. Our researches will be helpful for the theoretical and experimental study of the photodetachment of molecular anion.

• Abstract

Based on the 1²A" global three-dimensional adiabatic potential energy surface [Boggio-Pasqua et al., Phys Chem. Chem. Phys 2:1693-2000], a theoretical study of the stereodynamics of the reaction C(^3P)+CH(X^2Π) (v=0; j=0-6) has been performed using the quasi-classical trajectories(QCT) method. The cross sections are caculated. The differential cross sections (DCSs) and the distributions of P(θ_r), P(Φ_r) are pensented in detail at the selected collision energy of 0.3 eV. The product rotational alignment parameter ‹ P2(j' ⋅ k)› are also obtained as a function of the regent rotational quantum number. The results show that the reagent rotational excitation plays an important role in the title reaction.

• Abstract

Quasi-classical trajectory (QCT) calculations for the reaction S+H_2(v=0-2, j=0) → SH+H have been performed in order to investigate the effect of initial vibrational states on both the scalar and vector properties. The integral cross sections, opacity function have been calculated. The results indicate that the reaction probability and the cross section increase as the initial vibrational quantum number increases. The vibrational distributions and rotational distributions at different vibrational excited states are presented, and the results are discussed in detail. In addition, the vector properties, involving scattering directions of reaction product and the alignment and orientation of rotational angularmomentum, are calculated and discussed. The results indicate that the vibrational excited states have a positive effect on the forward scattering direction of the product, and the vibrational excited states have slight effect on the alignment and orientation of the rotational angular momentum.

• Abstract

An algebraic method is proposed to generate a self-consistent converged complex polarizability of atoms and molecules from limited available data. An iterative method is also suggested to generate the general accurate local field models of condensed systems. The effect of the local fields on the photoabsorption cross sections as the functions of the media density and structures has been studied in the present work. A substantial influence on the photoabsorption cross section has been found when the media density exceeds a critical density in the present unique model.