Thermal rate coefficients for the title reactions computed using a quasi-classical trajectory method on an accurate global potential energy surface fitted to ∼81,000 high-level ab initio points are compared with experimental values measured between 100 and 600 K using a variable temperature selected ion flow tube instrument. Excellent agreement is found across the entire temperature range, show...

We compute the rotational quenching rates of the first 81 rotational levels of orthoand paraH2CO in collision with orthoand para-H2, for a temperature range of 10–300 K. We make use of the quantum close-coupling and coupled-state scattering methods combined with the high accuracy potential energy surface of Troscompt et al. Rates are significantly different from the scaled rates of H2CO in coll...

We discuss the rate of an elementary chemical reaction. We use the reaction path and especially its saddle point on the potential energy surface. The reaction path connects reactant and product of a reaction over the transition state (TS). Usually, the TS is assumed near or at the single saddle point of the reaction path. By means of comparison of the statistics of states at the reactant and at...

I discuss the general scheme and background for Monte Carlo random walks. This is then applied this to the specific case of sampling the “roaming region” of the formaldehyde (H2CO) potential energy surface.

A study of a single acetylene adsorbed onto the Si(100)-(2×1) surface is presented. A MCSCF+MRMP2 wave function is used to study this system, which is shown to be significantly multiconfigurational over large sections of the potential energy surface. The lowest energy isomer is shown to have the acetylene adsorbed directly above a single dimer, di-σ, where the silicon−silicon dimer bond remains...

Thermal rate coefficients for the title reactions computed using a quasi-classical trajectory method on an accurate global potential energy surface fitted to ∼81,000 high-level ab initio points are compared with experimental values measured between 100 and 600 K using a variable temperature selected ion flow tube instrument. Excellent agreement is found across the entire temperature range, show...

Ab initio perturbed ion calculations were performed for the cubic, orthorhombic, hexagonal, and monoclinic phases of PbF2. A complete characterization of these phases was achieved in terms of the potential energy surfaces, the equations of state, and the phase-transition pressures. Thermal effects were included via a quasiharmonic nonempirical Debye model. The internal parameters of the unit ce...

We propose a procedure to determine the effective nuclear shell-model Hamiltonian in a truncated space from a self-consistent mean-field model, e.g., the Skyrme model. The parameters of pairing plus quadrupole-quadrupole interaction with monopole force are obtained so that the potential energy surface of the Skyrme HartreeFock + BCS calculation is reproduced. We test our method for N = Z nuclei...

We have used a discrete variable representation (DVR) with absorbing boundary conditions (ABC) to calculate initial state-selected reaction probabilities and photodetachment intensities. We apply this method to the OH + H, reaction constrained to a plane with the OH bond frozen. The calculated reaction probabihties have al1 the qualitative features observed in full dimensional calculations. We ...

A modified ab initio potential energy surface ~PES! is used for calculations of ozone recombination and isotopic exchange rate constants. The calculated low-pressure isotopic effects on the ozone formation reaction are consistent with the experimental results and with the theoretical results obtained earlier @J. Chem. Phys. 116, 137 ~2002!#. They are thereby relatively insensitive to the proper...