Molecular modelling of poly(aryl ether ketones). I. Aryl..aryl interactions in crystal structures.

Non-bonded potentials for the aryl..aryl interaction have been derived using crystal structure data of a number of small aromatic molecules. The potentials, based on atom-centered interactions, give an accurate reproduction of the benzene crystal geometry and sublimation energy when used in conjunction with coulombic energies evaluated using point atomic charges. An examination of the charge distribution on benzene suggested values of 0.13e (H) and -0.13e (C) to be suitable. The transferability of the potentials has been shown by prediction of crystal geometries and sublimation energies of other hydrocarbon molecules and, with additional interactions for the oxygen atom included, preliminary polymer crystal structure calculations have been carried out. These demonstrate the validity of the derived parameters by successfully predicting crystallographic unit cell dimensions and ring conformations in the poly(phenylene oxide) and poly(aryl ether ketone) crystals.