Order parameter angular overlap

The angular-overlap model (AOM) is one such specific model whose parameters have been chosen so as to refer to the central ion-to-ligand bonding process (9). However, it must be remembered that AOM still is a first-order perturbation model (70) but, one may say, a zeroth-order molecular orbital model (5). 

Another, less costly, unique alternative is the introduction of an angular overlap order parameter. Before we define it, let us first discuss the characteristic features of free-energy landscape parametrized by angular degrees of freedom. 

Such a variant is the angular overlap order parameter [46,47,189,195,196]. It is based on the idea of defining a simple and computationally low-cost measure for the similarity of two conformations, where the differences of the angular degrees of freedom are calculated. We define the overlap parameter as follows ... 

Another suitable parameter is the angular overlap parameter Q X) introduced in Section 9.1. The advantage is that it is particularly useful for classifying intermediate or metastable structures with stable but non-native contacts. In Fig. 9.6, the fluctuations of both parameters, i.e., d q)/dT and d Q)/dT, respectively, are plotted as functions of the temperature for the GoL model of sequence 20.6. We see clearly that the temperature region of conformational activity as signaled by these two order parameters coincides with the thermally active region indicated by the peak of the specific heat, which is also shown for comparison. The folding temperature, i.e., the temperature of maximum activity, is Tf 0.36. 

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