Calculations and Simulated Spectra

Poly(methyl methacrylate) (PMMA) is a vinyl polymer with two sidegroups, one of which is extended (COOCH3) and has internal degrees of freedom (Fig. 7). The geometry of a PMMA segment is determined not only by the main chain dihedral angles and the chirality Xi of the quaternary carbons, but also by the orientation Xi of the extended sidegroups with respect to the 

We will be interested only in the central carbon atoms Q (quaternary), CH3 (methyl sidegroup), and COO (carboxylic group). The methylene and the methyl ester (OCH3) peaks overlap experimentally. Therefore, they are both omitted from the present analysis. For our purposes, we consider the two terminal CH3 groups (which symbolize the continuation of the chain) as 

The six states of the main chain dihedral angles take the values given in Table 11. As in aPP and PVC, the sense of rotation depends on the chirality of the substituted carbon atom. 

The statistical weights depend only on the main chain dihedral angles and not on the sidegroup orientation This is a simplification, chosen in [24] to obtain a manageable model. 

The bond angles do depend on the dihedral angles in a characteristic way. In our approach, this feature is automatically introduced by the empirical force field. 

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