The equilibrium geometries, potential energy curves, spectroscopic dissociation energies of the ground and low-lying electronic states of He2, He2^＋ and He2^＋＋ are calculated using symmetry adapted cluster/symmetry adapted cluster-configuration interaction （SAC/SAC-CI） method with the basis sets CC-PV5Z. The corresponding dissociation limits for all states are derived based on atomic and molecular reaction statics. The analytical potential energy functions of these states are fitted with Murrell-Sorbie potential energy function from our calculation results. The spectroscopic constants Be, αe, ωe, and ωeχe of these states are calculated through the relationship between spectroscopic data and analytical energy function, which are in well agreement with the experimental data. In addition, the origin of the energy barrier in the ground state X^I∑9^＋ of He2^＋＋ energy curve are explained using the avoided crossing rules of valence bond model.
The reaction mechanism and kinetics for the addition of hydroxyl radical （OH） to phenol have been investigated using the hybrid density functional （B3LYP） method with the 6-31＋＋G（2dp, 2dr） basis set and the complete basis set （CBS） method using APNO basis sets, respectively. The equilibrium geometries, energies, and thermodynamics properties of all the stationary points along the addition reaction pathway are calculated. The rate constants and the branching ratios of each channel are evaluated using classical transition state theory （TST） in the temperature range of 210 to 360 K, to simulate temperatures in all parts of the troposphere. The ortho addition pathway is dominant and accounts for 99.8%-96.7% of the overall adduct products from 210 to 360 K. The calculated rate constants are in good agreement with existing experimental values. The addition reaction is irreversible.
