Trimer conformational distribution

Rg.5 Schematic representation of the crystal-nematic (CN) and nematic-isotropic (NI) transitions, illustrated for a trimer liquid-crystal system. The conformational distribution of the spacer remains quite stable in the nematic phase, and is termed nematic conformation... 

Figure 7 shows the distributions of (f in the isotropic phase of the simulated systems at temperatures close to the nematic/isotropic transition points. The distributions are practically featureless in the case of systems To and Tb (minor differences for these two systems are explained in Ref. [46]), while all features observed in the curves for systems T5 and Tq are seen to follow closely in position and intensity those present in the corresponding curves of Figure 4. Therefore, the distributions of

The intensities of the 83/2 and Pi/2 fluctuation bands in Figure 8 are in the ratio 2 to 1, virtually a statistical distribution however, the relative Intensity distributions for the Pi/2 and Pa/2 fluctuation bands differ notably. Much more pronounced differences are observed for the "hot bands" depicted in Figures 6 and 7 where the P3/2/ Pi/2 ratio varies with exciting frequency and in many instances approaches 8/1. This difference in intensity ratio must reflect very different geometries for the lower discrete states from which pumping occurs in bound-free transition. Again such a result would appear to correlate well with the theoretical analysis of the sodium trimer surface. Martin and Davidson predict that a linear symmetric conformation lies only 1050 cm above the ground... 

Figure 11b show a skewed conformation for such a trimer found in the mineral kilchoanite that is best formulated as Cae( Si04)( S130jq) [154]. Besides this skewed trimer an isolated monomer is found which displays a partial charge distribution very similar to that found in orthosilicate structures. The calcium-atoms have nearly their Ml ionic charge but in contrast to the... 

As discussed in Ref. [46], the simulated trimers are complex entities with a wide distribution of molecular shapes. Since different shapes have to be oriented differently in the nematic phase, a complete description of the order in this phase can be given only by taking simultaneously into account orientation and conformation, which is not an easy task. A simplified, but less complete description can be given if orientational and conformational orders are individually considered. Figure 6 shows the orientational distribution of the rigid groups with respect to the nematic director (the z axis) for the nematic phases at temperatures close to the transition points. The plot for system Tf, refers to the metastable... 

Dimers of series I have been simulated using the methods and parameters described for the trimers, except for the conformational terms. Distributions of r and ip appropriate to confer on the simulated dimers conformational characteristics similar to those of dimers of series I with n = 6 and n = 7 have been obtadned by analyzing the results of atomistic Monte Carlo calculations for the molecular fragments... 

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