Classical dynamics of chemical reactions in a quantum spirit

The dynamics of the 18 While the QCT calculations captured the experimental product vibrational energy distribution better than the QS method, the QCT results underpredicted rotationally-excited products, overpredicted forward-bias and predicted a trend in the strength of forward-bias with collision energy opposite to that measured, indicating that it does not completely capture the dynamic behavior measured in the experiment. Thus, these results further underscore the need for improvement in theoretical treatments of dynamics on the O 3 (X 1 A') PES and perhaps of the PES itself in order to better understand and predict non-statistical effects in this reaction and in the 3 formation of ozone (in which the intermediate O 3 * complex is collisionally stabilized by a third body). The scattering data presented here at two different collision energies provide important benchmarks to guide these improvements.

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

The non-statistical dynamics of the 18O + 32O2 isotope exchange reaction at two energies

Wyngarden

Mar

Quach

et al. 2014

“…However, the original Gaussian Binning method 23 has a major practical drawback represented by the exponential scaling of the number of data needed with the number of modes of vibration: for every quantum action, in fact, a Gaussian weight is provided and the total weight is given by the product of as many Gaussians as the modes of vibration. To overcome this issue, a simplified version of Gaussian Binning, called 1GB and based on a single Gaussian for the total vibrational energy has been proposed, 24 and shown to be equivalent to the original Gaussian Binning when the distribution of products in action space is smooth 25,26 and significantly more accurate and realistic than HB in a number of applications. 24,26,27 An interesting, and as we hope to demonstrate here, important difference between the 1GB and GB methods is the explicit use of the classical vibrational energy in the weight in the former.…”

Section: Introductionmentioning

confidence: 99%

A novel Gaussian Binning (1GB) analysis of vibrational state distributions in highly excited ${\rm H}_\text{2}$H2O from reactive quenching of OH* by ${\rm H}_\text{2}$H2

Conte

Kamarchik

et al. 2013

As shown in experiments by Lester and co-workers [J. Chem. Phys. 110, 11117 (1999)], the reactive quenching of OH* by H 2 produces highly excited H 2 O. Previous limited analysis of quasiclassical trajectory calculations using standard Histogram Binning (HB) was reported [B. Fu, E. Kamarchik, and J. M. Bowman, J. Chem. Phys. 133, 164306 (2010)]. Here, we examine the quantized internal state distributions of H 2 O in more detail, using two versions of Gaussian Binning (denoted 1GB). In addition to the standard version of 1GB, which relies on the harmonic energies of the states (1GB-H), we propose a new and more accurate technique based on exact quantum vibrational energies (1GB-EQ). Data from about 42 000 trajectories from previous calculations that give excited water molecules are used in the two versions of 1GB as well as HB. For the vibrationally hot molecules considered in this study, the classical internal energy distribution serves as a benchmark to estimate the accuracy of the different binning methods analyzed. The 1GB discretization methods, especially the one using exact quantum energies, reconstruct the classical distribution much more accurately than HB and also the original, more elaborate Gaussian Binning method. Detailed quantum state distributions are presented for pure overtone excitations as well as several antisymmetric stretch distributions. The latter are focused on because the antisymmetric stretch has the largest emission oscillator strength of the three water modes. © 2013 AIP Publishing LLC. [http://dx

“…35,36,43 The vibration of the formed H 2 molecules has been semiclassically quantized via the Gaussian weighting procedure. [57][58][59] In order to rationalize nonadiabatic effects upon scattering, molecular dynamics simulations are performed within the Born-Oppenheimer static surface (BOSS) approximation and within the local density friction approximation (LDFA). 60 In the former case, neither energy exchange with the surface phonons nor electronic excitations are accounted for.…”

mentioning

confidence: 99%

Communication: Hot-atom abstraction dynamics of hydrogen from tungsten surfaces: The role of surface structure

Galparsoro

Busnengo

Juaristi

et al. 2017

Adiabatic and non-adiabatic quasiclassical molecular dynamics simulations are performed to investigate the role of the crystal face on hot-atom abstraction of H adsorbates by H scattering from covered W(100) and W(110). On both cases, hyperthermal diffusion is strongly affected by the energy dissipated into electron-hole pair excitations. As a result, the hot-atom abstraction is highly reduced in favor of adsorption at low incidence energy and low coverages, i.e., when the mean free path of the hyperthermal H is typically larger. Qualitatively, this reduction is rather similar on both surfaces, despite at such initial conditions, the abstraction process involves more subsurface penetration on W(100) than on W(110).