Neon model calculation

The coefacient oi viscosity of neon as calculated for several molecular models, after Hirschfblder et al [1954]... 

Fig. 2.4. The asymptotic behaviour of the IR spectrum beyond the edge of the absorption branch for CO2 dissolved in different gases (o) xenon (O) argon ( ) nitrogen ( ) neon (V) helium. The points are experimental data, the curves were calculated in [105] according to the quantum J-diffusion model and two vertical broken lines determine the region in which Eq. (2.58) is valid.

In fact, this mechanism has been confirmed by a calculation of the cross sections for impact ionization and impact excitation in electron-ion collisions [36]. The latter was found to be exceptionally low for neon. The basic features of recollision excitation follow from an amplitude such as (4.1) with, however, integration over one additional time the first electron tunnels out at the time t", recollides, promotes the bound electron into an excited state with energy Eq2 > E02, and leaves the interaction region at the time t > t", while the bound electron only becomes free at the later time t > t. Figure 4.5 exhibits the results of such a model. Indeed, for a sufficiently high-lying excited state, the region around zero ion momentum is filled in. 

By performing MD simulations of ND3 at ambient temperatures, using a fully flexible model and calculating the EFG for randomly chosen ammonia clusters we were able to obtain results -3.67 MHz and 245 kHz, respectively at 271 K. The results were obtained after increasing the cluster size to full convergence and at the MP2 level of approximation, corrected with full Cl values. Similar calculations [45-48] have been reported for liquid water and for Ne in liquid neon with very good results. 

In Table 4 we present results from the calculation on the neon dimer. The equilibrium distance of the potential is not determined in this work. But based on previous experience with extended geminal models, say on the He2 dimer [45] and the Be2 dimer [47], we can safely assume that the equilibrium distance obtained by a geometry optimization, is close to the experimental value. Hence, the quantity —U (R = 5.84 au), where U(R) is the interatomic... 

The extended geminal models have two main advantages. First, the conceptual structure which facilitates interpretation. This property is utilized in several studies on intermolecular interactions where energy decomposition schemes illuminate the character of the bonding. Second, the models are highly accurate. This feature is related to the FCI corrections on which the models are based. The reported calculations on few-electron systems illustrate this point. However, as demonstrated by the calculation on the neon dimer reported in this work, a high accuracy of a calculation on larger systems, require that at least triple pair corrections are included. 

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