Wang Mei-Shan

Collision Energies Effect on Stereodynamics for Ne+H 2 + →NeH + +H Reaction

Vector correlation between reagents and products for the reaction Ne + H+2 → NeH+ + H is studied using quasi-classical trajectory method at different collision energies on a new surface constructed by Lv et al.[J. Chem. Phys. 132 (2010) 014303] The results of angular distributions P(θr) and P(r) show that the product rotational angular momentum is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The four polarization-dependent generalized differential cross sections show that the scatting direction of product NeH+ is significantly affected by the collision energy.

Photo-detachment cross section of H- near two parallel interfaces

The photo-detachment cross section of H− near two parallel elastic interfaces is derived and calculated by using the closed orbit theory. The photo-detachment cross section of H− near two interfaces is shown to exhibit multi-periodic oscillations when the distance between the H− and the interface is varied. Each peak in the Fourier transformed photo-detachment cross section corresponds to the length of a closed orbit, which is quite similar to the case of atomic spontaneous emissions in a dielectric slab. This study provides a new understanding of the photo-detachment process of H− in the presence of interfaces.

Electronic structure and optical properties of Al and Mg co-doped GaN

The electronic structure and optical properties of Al and Mg co-doped GaN are calculated from first principles using density function theory with the plane-wave ultrasoft pseudopotential method. The results show that the optimal form of p-type GaN is obtained with an appropriate Al:Mg co-doping ratio rather than with only Mg doping. Al doping weakens the interaction between Ga and N, resulting in the Ga 4s states moving to a high energy region and the system band gap widening. The optical properties of the co-doped system are calculated and compared with those of undoped GaN. The dielectric function of the co-doped system is anisotropic in the low energy region. The static refractive index and reflectivity increase, and absorption coefficient decreases. This provides the theoretical foundation for the design and application of Al—Mg co-doped GaN photoelectric materials.

Ab initio calculations of the ionization spectrum of SO2

The ionization spectrum of sulfur dioxide has been successfully studied by using the symmetry-adapted-cluster configuration-interaction (SAC-CI) general-R and SD-R methods and the basis set correlation-consistent polarized valence triple-zeta (cc-pVTZ). The SAC-CI general-R method reproduces the experimental spectrum well for both the main peaks and the satellite peaks of ionization spectrum of SO2. The sequence of ionic states corresponding to main peaks of SO2 has been re-determined according to the SAC-CI conclusions and it is reordered as 2A1, A2B2, 2A2, 2B1, 2A1, Ē2B2 and 2A1. Besides, the equilibrium structures and adiabatic ionization potentials (AIPs) of ionic states of main peaks of SO2 are calculated by using the SAC-CI SD-R method.

Comparative study of adsorption characteristics of Cs on the GaN (0001) and GaN (0001̄) surfaces

The adsorption characteristics of Cs on GaN (0001) and GaN (000) surfaces with a coverage from 1/4 to 1 monolayer have been investigated using the density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations. The results show that the most stable position of the Cs adatom on the GaN (0001) surface is at the N-bridge site for 1/4 monolayer coverage. As the coverage of Cs atoms at the N-bridge site is increased, the adsorption energy reduces. As the Cs atoms achieve saturation, the adsorption is no longer stable when the coverage is 3/4 monolayer. The work function achieves its minimum value when the Cs adatom coverage is 2/4 monolayer, and then rises with Cs atomic coverage. The most stable position of Cs adatoms on the GaN (000) surface is at H3 site for 1/4 monolayer coverage. As the Cs atomic coverage at H3 site is increased, the adsorption energy reduces, and the adsorption is still stable when the Cs adatom coverage is 1 monolayer. The work function reduces persistently, and does not rise with the increase of Cs coverage.

Dynamic mechanism for encapsulating two HIV replication inhibitor peptides with carbon nanotubes

Encapsulation of biomolecules inside a carbon nanotube (CNT) has attracted great interest because it could enable the delivery of nanoscale pharmaceutical drugs with CNT-based devices. Using a molecular dynamics simulation, we investigate the dynamic process by which human immunodeficiency virus (HIV) replication inhibitor peptides (HRIPs) are encapsulated in a water solution contained inside a CNT. The van der Waals attraction between the HRIPs and the CNT and the root-mean-square deviation are used to analyse the evolution of the encapsulation. It is found that the interaction between the HRIPs and the CNT is the main driving force for the encapsulation process, which does not cause an obvious conformational change to the HRIPs.

Stereodynamics of the reactions Ne+H+2/Ne+D+2/Ne+T2

The vector correlations between products and reagents for the reactions Ne+H+2, Ne+D+2, and Ne+T+2 are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lu et al. [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), and (2π/σ)(dσ21−/dωt), and the distributions of P(θr), P(r), and P(θr, r) are calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.

Ab initio investigations of the charge transport properties of endohedral M @C 20 ( M= Na and K) metallofullerenes

Using density functional theory and quantum transport calculations based on nonequilibum Greens function formalism, we investigate the charge transport properties of endohedral M@C20(M = Na and K) metallofullerenes. Our results show that the conductance of C20 fullerene can be obviously improved by insertion of alkali atom at its centre. Both linear and nonlinear sections are found on the I—V curves of the Au-M@C20-Au two-probe systems. The novel negative differential resistance behaviour is also observed in Na@C20 molecule but not in K@C20.

Theoretical study on the complexes of He, Ne and Ar

This paper investigates the effect of basis sets through the potential energy curves (PECs) of six rare gas complexes He2, Ne2, Ar2, He—Ne, He—Ar, and Ne—Ar. The coupled cluster singles and doubles method with perturbative treatment of triple excitations, doubly augmented basis sets of d-aug-cc-pVQZ, bond functions, and basis set superposition errors are employed. The diffuse function is more effective than the polarization function on describing the dissociation energy. The PECs are fitted into analytical potential energy functions (APEFs) using three expressions. It is found that all the expressions are suitable for describing the complexes of rare gases. Based on these APEFs, the spectroscopic parameters are calculated and the results are compared with the theoretical and experimental data available in the literature.

Control of reaction channels of CsI molecule by ultra-short laser pulse

The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.