The line intensities of 0300 a—0000 s transition of the symmetric-top NH3 molecule at high temperature were obtained by directly calculating the partition functions while regarding the rotationless transition dipole moment squared as a constant. The calculated values of the total internal partition sums (TIPS) are consistent with the data of HITRAN database within 0.19% at 296 K. The calculated line intensities data at 2000 K and 3000 K are also in excellent agreement with the data in HITRAN database with discrepancies less than -0.65% and -1.77%, which strongly supports the calculations of partition function and line intensity at high temperature. Then we extended the calculation to higher temperature. The line intensities and simulated spectra of 3ν2 band of the symmetric-top NH3 molecule at 4000 K and 5000 K were reported. The results are of significance for the study of the high-temperature molecular spectra in experiment and in theory.

No abstract

The electronic structure of CaB 2 O 4 (III) crystal obtained by using SIESTA program is reported in this article. It is observed that the band gap values are, respectively, 5.39 and 5.89 eV from our LDA and GGA calculations. The bond covalency and bond valence are calculated with a simplified method. For both Ca-O and B-O types of bond, the bond covalency has a decreasing trend with the increasing bond length. The result of bond covalency in explaining the interaction between atoms has been shown in good agreement with that of Mulliken population analysis. The ionic configuration for CaB 2 O 4 (III) in the fundamental state is estimated to be Ca ?1.808 B -0.68 O -0.112 . A summary of B-O distances for the four phases of CaB 2 O 4 crystal from several works is also presented.

Wang Zhen-Ya(王振亚) c) , Zhang Jie(张 杰) a) , and Yu Chun-Ri(余春日) a)

An anisotropic intermolecular potential of the He-HF complex has been obtained by utilizing the BFW analytic function to fit the intermolecular energy data, which have been calculated at the theoretical level of the single and double excitation coupled-cluster method with noniteractive perturbation treatment of triple excitation CCSD (T). And the reliability of the potential has been verified by comparing it with other potential models. The differential, partial and total scattering cross sections for collisions between He atoms and HF molecules have been calculated respectively by using the quantum close-coupling method at five different potential models, and the calculated results have been compared and analysed in detail. The research shows that the scattering cross sections are sensitive to the position where potential is zero, the well depth, the strength of the repulsive wall of the spherically averaged and to the anisotropy of the region of the well depth. We hope that the results can provide profitable reference for determining exactly the interaction potential of the atomic-molecular collision systems from the scattering cross sections.