Light atom anomaly

What seemed to be a similar "energy anomaly had been reported by Blais and Bunker [303]. They also found that there was a reduction in the vibrational energy yield when A was light but their potential possessed considerable long-range attraction. However, this effect did not survive a modification of their potential and the extension of the calculations to three dimensions [305]. Nevertheless, the exact conditions under which the light-atom anomaly appears are not yet entirely clear. Calculations by Bunker and Parr [319] on a wide-corner potential, that is, one on which the reaction path on the collinear surface cuts the corner [210], showed no indication of the light-atom anomaly, and it seems that still more study will be required before the interrelations between the way different surfaces display this phenomenon can be completely understood [319],... 

Here, the optimum distribution of energy is S0% in the HCl vibration with most of the balance in relative translation. Further vibrational excitation at the expense of relative translational energy reduces the likelihood of reaction. This is a manifestation of the light atom anomaly , that is the unusual dynamical behaviour that appears when the attacking atom in an exothramic reaction or the product atom in an endothermic reaction, i.e. atom A, is much lighter than the other two, i.e. B and C. 

Reaction (21) is omitted from Table 1 because the product state vibrational distribution does not yield a linear surprisal plot. It appears that this is another manifestation of the light atom anomaly referred to earlier. In particular it should... 

The dynamical features associated with the light atom anomaly, e.g., direct mechanism without snarled trajectories (except for XX cases) and short reaction times compared with the vibrational periods of molecular vibrations have made the H + X2 reactions a favorite for development of models for impulsive energy release.The approximately collinear reaction configuration (at least for F2 and CI2) provide n incentive to those interested in rigorous one-dimensional quantum lodels. " The nonlinear surprisals also have been a stimulus for work based upon the information-theoretic approach. The vibrational (especially so for the onedimensional base and translationaF " surprisals are approximately quadratic, rather than linear. These distributions can be understood in terms of an additional constraint, which is termed a Franck-Condon-like or momentum transfer constraint. Introduction of this constraint leads to a... 

Fig.7.2. Calculated and measured equilibrium atomic raddi for the light actinide metals [7.6]. The decreasing radii in the beginning of the series, Ac-Pu, are caused by increasing occupation of bonding 5f states while the calculated anomaly between Pu and Am is due to the onset of spin polarisation...

Despite this anomaly, the complex angular-momentum function can be used to rationalize many features of stereochemistry. It represents the only vector quantity in wave mechanics which could interact with an applied magnetic field. It accounts for the so-called Faraday effect, which is a property of achiral molecules in an applied magnetic field to rotate the plane of polarised light. It is easy to demonstrate that atomic orbital angular-momentum vectors always line up antiparallel... 

Some information about the valence state of the lanthanoid atoms in their compounds shows the dependence of the lattice parameters due to the change of the R atomic number. All the rare earths may be considered for monophosphides with the NaCl-type structure (fig. 20). Using the listed data one can make conclusions about the R valence state of all the rare earths. A small deviation from a linear dependence of the lattice parameter vs. atomic number is observed only for cerium monophosphide. This anomaly is probably due to an intermediate valence of cerium atoms between Ce + and Ce" ". For the light rare-earth pentaphosphides we consider the change of the unit-cell volumes which correspond to one formula units. The variation is caused by the RP5 phosphides belonging to two structure types with a different number of formula units per unit cell. As one can see (fig. 20b) a linear dependence indicates the trivalent state of the R atoms in these compounds. 

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