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The expansion coefficient CD|L| of Coulomb potential 1/r12 of atomic system in hyper-spherical harmonics is derived and the explicit expression is given.

Quantum dynamical calculations for the IR-multiphoton excitation of H2O, D2O and T2O are presented using a generalized Hamiltonian for XY2 molecules. The energy spectra obtained from this Hamiltonian are in good agreement with those of the experiments. The long time average of the transition probabilities and the isotopic effects are discussed in detail

A new quantum scattering approach (linear combination of arrangement channels-scattering wavefunction, LCAC-SW) proposed by Deng and his co-workers is used to calculate collinear state-to-state reaction probabilities for the F + H2(v) HF(v') + H system. Several interesting problems such M threshold energy, compound states and enhance by translational energy of the reactants and the vibration excitation of products are discussed and they are compared with other theoretical investigations reported in the literature. It is shown that the LCAC-SW approach is the successful one of quantum scattering methods.

The structures of lithochlorosilylenoid H2SiLiCl have been studied by RHF/STO-3G gradient method. Four equilibrium states and three isomerization transition states are located. The calculation shows that the structure with three-membered ring is the most stable one and the stability of the equilibrium structures is in the order of three-membered ring >p-complex>σ-complex>tetrahedron. The dipole moments, Mulliken populations, frontier molecular orbitals and peculiarities of various structures are also given and analyzed.

The structures of singlet stannylenoid H2SnLiF have been examined by ah initio MO theory. Four equilibrium states and three transition states of isomerization reaction are located. The calculation shows that the p-complex 1 is the most stable and experimentally detectable. The other three species, three-membered ring 2, s-complex 3 and tetrahedron 4, are also local minima on the potential energy surface, but are higher in energy.

This paper has improved Hickman's nonadiabatic collision model by substituting Hickman's constant velocity classical straight line trajectory approximation with the solution of motion equation mR=−dV(R)/dR, and has calculated the cross sections of ion-pair formation Cs+O2Cs++O−2 with the improved nonadiabatic collision model (INCM). A comparison of our results with other theoretical and experimental results has been made.

The matrix elements of the correlation function between symmetric potential harmonics am simplified into the analytical summations of the grand angular momenta by dy using the recurrence and coupling relations of the potential harmonics. 'The correlation-function potential-harmonic and generalized-Laguerre-function method (CFPHGLF), recently developed by us, is applied to the S states of the helium-like systems for Z = 2 to 9. The results exhibit good convergence with the bases in tern of both the angular and radial directions. The final eigen-energies agree excellently with the best s-limits of the variational configuration interaction (CI) method for the involved low-lying S states. The accuracy of the potential harmonic (PH) expansion scheme is discussed relative to the exact Hylleraas CI results (HCI), and Hartree-Fock results. Moreover, suggestion is given for the future improvement of the PH scheme.

The Lewis acidity scale of boron trihalides BX3 (X=F, C1, Br, I) and character of the boron-halogen bonds have been studied by means of DV-Xm approach. Present results show that the acid strength of boron trihalides increases in the order BF3

On the basis of the common feature among the electron transfer process and the ion hydration process as well as the relevant experimental kinetic data of electron trader reaction, a new accurate hydration potential function scheme for the determination of electron transfer coupling matrix element is presented. The coupling matrix element between two hydrated ions of the reacting system in solution is calculated. The results and the applicability of this scheme are discussed.

1,2-rearrangements of carbenes: CCH2X(X = CH2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X = CH8>NH>0. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.

Novel structures of H2CCCLiX (X F, Cl) were determined using HF/STO-3G gradient method. Both of the carbenoids have two equilibrium structures, askew and linear forms, at the level of calculation. In the case XF, the former is more stable, but in the case X=Cl, the latter is more stable. The frontier MOs are given and analyzed.

Isomerizations of cyclobutylidene 1 to methylenecyclopropane 2, cyclobutene 3 and bicyclobutane 4 have been studied using ab initio method. Equilibrium and transition structures are fully optimized with 3–21G basis set. The reaction barriers are 78, 75 and 110 kJ/mol at 6–31 G**, respectively, 12 occurs via the outward disrotation of two end C-C bonds, 13 via the attack of an exo hydrogen to the carbene p AO before the transition state, and 14 is unable to compete with 12 and 13 for its higher barrier.