Quasi-Classical Trajectory–Gaussian Binning Study of the OH + D₂ → HOD(v₁′,v₂′,v₃′) + D Angle–Velocity and Vibrational Distributions at a Collision Energy of 0.28 eV

Abstract

The angle-velocity and product vibrational state distributions for the OH + D(2) reaction at a collision energy of 0.28 eV have been calculated using the quasi-classical trajectory-gaussian binning (QCT-GB) method and the Wu-Schatz-Lendvay-Fang-Harding (WSLFH) analytical potential energy surface. Comparison with high resolution molecular beam experiments shows that, differing from what happens when using the standard QCT method (i.e., histogram binning), very good results are obtained for both distributions. Hence, the strong differences previously observed between QCT and experimental results mainly come from an inadequate pseudoquantization of HOD rather than from other quantum effects. This is probably the first time that such a high level of agreement between theory and high resolution experimental data has been found in polyatomic reaction dynamics.

Classical dynamics of state-resolved hyperthermal O(3P) + H2O(1A1) collisions

“…16,17 In the Gaussian binning procedure a single weight is used for each trajectory (1D-GB). 18 With these procedures, Sierra et al 11 obtained excellent agreement with angle-velocity measurements of product D-atoms, showing distinct vibrational structure of product HOD bending and stretching modes. For (H 2 O) 2 and (D 2 O) 2 dissociation, Czako et al 12 use similar binning procedures, except the Gaussian weights are determined by vibrational energies instead of quantum numbers.…”

“…These have led to impressive results for several systems: CH 4 + Cl → HCl + CH 3 , 10 OH + D 2 → HOD + D, 11 (H 2 O) 2 and (D 2 O) 2 dissociation, 12 and rotational excitation of H 2 O by H 2 . 13 In particular for the reaction, OH + D 2 → HOD + D, Sierra et al 11 use standard QCT methods, plus two key advances: determination of vibrational quantum numbers through analysis of product momenta and coordinates, 14,15 and a Gaussian binning procedure which weights trajectories where classically determined vibrational quantum numbers are close to "allowed" quantum integer values. 16,17 In the Gaussian binning procedure a single weight is used for each trajectory (1D-GB).…”

When classical trajectories get to quantum accuracy: II. The scattering of rotationally excited H2 on Pd(111)

“…Since the early 2000s, two corrections have been introduced in the QCT method, namely, Gaussian binning [28][29][30][31][32][33] (GB) and the Adiabaticity correction (AC). 32,[34][35][36] GB introduces some pseudo-quantization in the QCT method by taking into account Bohr's condition of quantization for the final quantized degreesof-freedom.…”

Insights into the semiclassical Wigner treatment of bimolecular collisions

“…Quantum mechanical (QM) calculations of molecular reaction dynamics [1][2][3][4][5][6][7][8][9][10][11] are generally much heavier than quasi-classical trajectory calculations [12][13][14], in particular for polyatomic processes [15][16][17][18]. Hence, for several decades, intense researches aim at building semiclassical methods taking into account the largest quantum effects while keeping with the classical description of nuclear motions [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”