Group contribution models nonlinear

Lai, W. Y., D. H. Chen, and R. N. Maddox, Application of a Nonlinear Group-Contribution Model to the Prediction of Physical Constants 1. Predicting Normal Boiling Points with Molecular Structure. Ind. Eng. Chem. Res., 1987 26, 1072-1079. 

Lai, W.Y., Chen, D.H., and Maddox, R.N., Apphcation of a nonlinear group-contribution model to the prediction of physical constants. 1. Predicting normal boihng points with molecular structure, Ind. Eng. Chem. Res., 26, 1072-1079, 1987. 

A closer inspection of the individual group contributions shows that there are some nonlinear effects. The exchange of hydrogen in the X group against phenyl or cyclohexyl or the exchange of phenyl to cyclohexyl and vice versa depends on the groups that are already present in X (Table 3). A much simpler Free-Wilson model... 

Azeotropic behavior is not limited to binary systems only. Also ternary and quaternary azeotropic points are observed. For the determination of the azeotropic points in ternary and quaternary systems, thermodynamic models (g -models, equations of state, group contribution methods) can again be applied [40]. Azeotropic points in homogeneous systems can be found with the help of nonlinear regression methods. At the azeotropic point all separation factors aij show a value of 1 in the case of homogeneous systems. This means that the following condition has to be fulfilled ... 

A detailed X-ray diffraction experiment and quantum-chemical calculations of N,N-dhnethyl-4-nitroaniline derivatives, also model compounds for optically nonlinear organic materials, revealed that the introduction of a substituent into the ortho- or meta-position with respect to the dimethylamino group resulted in decreasing the contribution of the... 

Another element contributing to the existence and types of oscillatory solutions is the nonlinearity of the system. A classification of known chemical models based on their nonlinearities is given below. It is shown that various models discussed in the literature by different investigators may be grouped in special classes. 

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