Diatomic molecules potential, intermolecular

As shown by Montroll and Shuler, Eq. (1) can be used to make a stochastic model for the dissociation of a diatomic molecule, but it is quite clear that this model will never be very realistic since the transition probabilities are too restrictive and the true intermolecular potential is quite different from a cutoff harmonic potential. A large number of papers which claim to improve the model with respect to these two deficiencies have been published,4 but we shall not be concerned with those here. 

Tanczos35 has extended the theory (for V-T and V-V transfer) to polyatomic molecules, and a detailed comparison with experiment was recently given by Stretton33. Considering each surface atom, energy transfer depends on how the intermolecular potential varies with the oscillation of the atom. In deriving the result for the diatomic molecule from the harmonic-oscillator wave functions, we substituted... 

The one-dimensional potential curves depicted in Figures 1.1-1.3 represent the dissociation of diatomic molecules for which the potential V(Rab) depends only on the internuclear distance between atoms A and B. However, if one or both constituents are molecules, V is a multidimensional object, a so-called potential energy surface which depends on several (at least three) nuclear coordinates denoted by the vector Q = (Ql,Q2,Q3,---) (Margenau and Kestner 1969 Balint-Kurti 1974 Kuntz 1976 Schaefer III 1979 Kuntz 1979 Truhlar 1981 Salem 1982 Murrell et al. 1984 Hirst 1985 Levine and Bernstein 1987 ch.4 Hirst 1990 ch.3). The intramolecular and intermolecular forces, defined by... 

If we want to predict the structure, the stability and the vibrational and rotational spectra of Van der Waals molecules, we have to know the complete intermolecular potential as a function of the intermolecular distanoe(s) and the molecular orientations. For rare gas dimers and for some rare gas atom-diatomic molecule (e.g. 

A test of this method for 1-D radial potentials is shown in Fig. 2. Here we have taken an assumed intermolecular potential (shown in solid line) for a weakly bound diatomic molecule (which for realism had well depths and radial minima similar to a psuedo diatomic treatment of Ar-HF), and solved exactly for the J = 0, 5, 10, 15, 20, 25, and 30 eigenvalues for v=0 by exact close coupling quantum calculations. These eigenvalues are then taken as input into the rotational RKR method, which attempts to regenerate the initial potential. 

The potential energy (PE) of multi-atomic species varies with intermolecular distances. Fig. 1.16 shows the generic one-dimensional PE cmve for a diatomic molecule. A triatomic molecule would require a two-dimensional surface, and polyatomics a multi-dimensional surface but the key features can be illustrated by reference to the diatomic PE curve. Vibrational energy spacings are in the order of 100-4000 cm , much smaller than electronic energy spacings, and transitions between vibrational levels can be induced by IR and NIR photons. Strong bonds... 

Repulsive Interactions (Harmonic Oscillator in a Box). In most stable solutions and in pure liquids where the components are at or near relatively deep intermolecular potential minima, attractive interactions dominate the intermo-lecular repulsive terms. Unstable solutions of large solute molecules dissolved in a solution of small solvent molecules can be prepared in the solid phase by trapping experiments. Certain trapped free radicals may therefore show the effects of solvent-solute repulsive interactions, which would be evidenced by blue shifts in the infrared spectrum of these cramped solutes. Diatomic carbon (C2) trapped in solid xenon shows this effect strongly (30, 31, 32) in both the upper and lower... 

What is the minimum number of coordinates necessary to describe completely the Intermolecular potential energy function of two linear molecules Assume that you can neglect any coordinates for the internal vibrations of each molecule. Give an example of such a set of coordinates. THINKING AHEAD [If we assume that the two molecules are both diatomics, how many coordinates are there altogether How many are for just the internal vibrations ]... 

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