Quasi-classical trajectory (QCT) calculations have been carried out to study the stereodynamics of the reactions H + LiH(+) (v = 0, j = 0) --> H(2) + Li(+) and H(+) + LiH (v = 0, j = 0) --> H(2)(+) + Li which proceed on the two lowest-lying electronic states of the LiH(2)(+) system, using the ab initio potential energy surfaces (PESs) of Martinazzo et al. [J. Chem. Phys., 2003, 119, 11241]. Differential cross sections (DCSs) and alignments of the product rotational angular momentum for the two reactions are reported. Though the two PESs employed in the current calculations have significant differences, the tendencies of the product rotational alignment are same on the whole, and some common features emerge. This interesting phenomenon probably indicates that, for this system, the characters of the PESs have a weak influence on the alignments of the products. The conclusion is confirmed by a further discussion of rotational alignment parameter which also indicates that the two PESs are repulsive, i.e., the exoergic processes of the reactions taking place on the exit valleys of the PESs.

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Two-photon-pumped amplified spontaneous emission (ASE) of CH3NH3PbBr3 microdisks (MDs) were investigated by using femtosecond laser system. Low threshold at 2.2 mJ cm(-2) was obtained. Also, emission spectral tunability from 500 to 570 nm was demonstrated by synthesis the mixed halide perovskite MDs. The spatial effect of photoluminescence (PL) properties under one-photon and two-photon excitation were also studied by means of two-photon laser scanning microscope (TPLSM) and time-resolved PL spectroscopy. It was found that the band to band emission of near-surface regions and photocarriers' diffusion from near-surface regions to interior regions is significant for one-photon excitation. By contrast, reabsorption of emission under two-photon excitation plays a major role in the emission properties of the MDs. These results will give a more comprehensive understanding of the nonlinear effect of CH3NH3PbBr3 single crystals.

Although there is plenty of research work being done in the field of carbon nanotube reinforced composite materials, no special attention has been paid to the factors of the polymer's repeat unit arrangement and conformation. In this paper we use molecular dynamics simulation based on a Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field to study the interactions between five types of polymers and (10, 10) single-walled carbon nanotubes (SWNTs). When we study the interactions, we pay special attention to the polymer's different repeat unit arrangements and different conformations. We find that the interaction strength between the poly(phenylacetylene) molecules and SWNTs is obviously influenced by these factors, and the degree of the poly(p-phenylenevinylene) wrapping around the SWNT is associated with its repeat unit arrangement. Based on the present simulations, we think that the nanocomposite should have high mechanical properties if the polymer with an appropriate repeat unit arrangement and conformation is used to form the first layer around the SWNT.

Employing the quasi-classical trajectory method and the potential energy surface of Panda and Sathyamurhy [Panda A N and Sathyamurthy N 2004 J. Chem. Phys. 121 9343], the effect of the reagent vibration on vector correlation of the ion—molecule reactions D− + H2 and H− + D2 is studied at a collision energy of 35.7 kcal/mol. Four generalized polarization-dependent differential cross sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), and (2π/σ)(dσ21−/dωt) are presented in the centre-of-mass reference frame, separately. At the same time, the effects on the product angular distributions P(θr), P(φr) and P(θr, φr) of the title reactions are also analysed. The calculated results show that the scattering tendencies of the product HD, the alignment and the orientation of j′ sensitively depend on reagent molecule vibration.

Using the multireference configuration interaction method with a Davidson correction and a large orbital basis set (aug-cc-pVQZ), we obtain an energy grid that includes 32 038 points for the construction of a new analytical potential energy surface (APES) for the Ne + H(2)(+) → NeH(+) + H reaction. The APES is represented as a many-body expansion containing 142 parameters, which are fitted from 31 000 ab initio energies using an adaptive nonlinear least-squares algorithm. The geometric characteristics of the reported APES and the one presented here are also compared. On the basis of the APES we obtained, reaction cross sections are computed by means of quasi-classical trajectory (QCT) calculations and compared with the experimental and theoretical data in the literature.

The potential energy curves (PECs) of the bound states of M-X (M=Cu, Ag, and Au and X=He, Ne, and Ar) complexes have been calculated using the coupled cluster singles and doubles method with perturbative treatment of triple excitations. Large basis sets and bond functions, as well as the basis set superposition errors, are employed to obtain accurate PECs. The analytical potential energy functions (APEFs) are fitted using the PECs. The vibrational energy levels and the spectroscopic parameters for the complexes are determined using our APEFs and compared to the theoretical works available at present. We also find that the PECs are bound with similar van der Waals interactions, which implies that He, Ne, and Ar may be used for buffer-gas cooling; and Cu, Ag, and Au may be trapped with a similar method because Cu and Ag have been experimentally trapped with He buffer-gas cooling.

The isotopic effects on stereodynamic properties for the title reactions occurring on the two lowest-lying electronic potential energy surfaces (PESs) of LiH(2)(+) are investigated in detail by means of the quasi-classical trajectory (QCT) method at a collision energy of 0.5 eV, using the ab initio potential energy surfaces (PESs) of Martinazzo et al. (J. Chem. Phys., 2003, 119, 11241). The corresponding reactions comprise: (i) H/D/T + LiH(+) --> HH/HD/HT + Li(+) and H + LiH(+)/LiD(+)/LiT(+) --> HH/HD/HT + Li(+); (ii) H(+)/D(+)/T(+) + LiH --> HH(+)/HD(+)/HT(+) + Li and H(+) + LiH/LiD/LiT --> HH(+)/HD(+)/HT(+) + Li. Differential cross sections (DCSs) and alignments of the product rotational angular momentum for all of these reactions are reported. The results illustrate that the reason for the abnormal behavior of the DCSs for the title reactions reported in the previous work is ascribed to the sensitive role of the projectile atomic mass, and indicate that the long-range interactions play a more important role than the mass factor in ion-molecule reactions. The current topic for this special mass combination system shows some new features of the stereodynamics differing from the previous studies for "typical" mass-combination reactions.