The Potential Energy Surface PES of (H2)2 dimer has been investigated, using five simple rigid rotor models. These models are called: head to head, symmetric side to side, L , steplike and T model. All calculations were done at two levels of ab initio  methods: MP2(Full) and QCISD (T,Full) using cc-pVTZ basis set at singlet state of spin multiplicity. The results of scanning PES were then fitte...

in this study, the interaction between no2+ cation and hen (n = 1-7) clusters is investigated by means of ab initio calculations at mp2/aug-cc-pvtz and qcisd/aug-cc-pvtz computational levels. the first and second solvation shells were obtained while n atom of no2+ interacts with five and two he atoms, respectively. stabilization energies of the studied complexes including basis set superpositio...

Saddle point properties of three symmetric and one asymmetric hydrogen transfer and the energy of reaction of the asymmetric reactions are investigated in the present work. These reactions were calculated by various density functionals, many of which were developed in recent years, by coupled cluster theory, and by multicoefficient correlation methods based on wave function theory. Instead of c...

Neutral hydrogen clusters are grown in ultracold helium nanodroplets by successive pickup of hydrogen molecules. Even-numbered hydrogen cluster cations are observed upon electron-impact ionization with and without attached helium atoms and in addition to the familiar odd-numbered H(n)(+). The helium matrix affects the fragmentation dynamics that usually lead to the formation of overwhelmingly o...

We have re-examined the B-N distance potential of CH3CN-BF3 using MP2, DFT, and high-accuracy multicoefficient methods (MCG3 and MC-QCISD). In addition, we have solved a 1-D Schrödinger equation for nuclear motion along the B-N stretching coordinate, thereby obtaining vibrational energy levels, wave functions, and vibrationally averaged B-N distances. For the gas-phase, MCG3//MP2/aug-cc-pVTZ po...

In this work, theoretical rate constants are estimated for mercury oxidation reactions by hydrogen chloride that may occur in the flue gases of coal combustion. Rate constants are calculated using transition state theory at the quadratic configuration interaction (QCI) level of theory with single and double excitations, and are compared to results obtained from density functional theory, both i...

The constrained density functional theory-configuration interaction (CDFT-CI) method has previously been used to calculate ground-state energies and barrier heights, and to describe electronic excited states, in particular conical intersections. However, the method has been limited to evaluating the electronic energy at just a single nuclear configuration, with the gradient of the energy being ...

We present direct ab initio dynamics studies of vibrational-state selected reaction rates of the OH1H2→H1H2O reaction. Rate constants for both the OH1H2~v51! and OH~v51!1H2 reactions were calculated based on a full variational transition state theory plus multidimensional semiclassical tunneling approximations within a statistical diabatic model. The potential energy surface information was cal...

We report benchmark calculations of reaction energies, barrier heights, and transition-state geometries for the reaction of CH(3)OH with H to produce CH(2)OH and H(2). Highly accurate composite methods, such as CBS, G2, G3S, G3X, G3SX, and multi-coefficient correlation methods (MCCMs), are used to calibrate lower-cost methods. We also performed single-level CCSD(T) calculations extrapolated to ...