Structure and dynamics of mesogens using intermolecular potentials derived from ab initio calculations

A method for the calculation of the two-body intermolecular potential which can be applied to large molecules is presented. Each monomer is fragmented in a number of moieties whose interaction energies are used to recover the interaction energy of the whole dimer. For these reasons this strategy has been called fragmentation reconstruction method (FRM). By a judicious choice of the fragmentation scheme it is shown that very accurate interaction energies can be obtained. The sampling of the potential energy surface of a dimer is then used to obtain intermolecular force fields at several levels of complexity, suitable to be employed in bulk phase computer simulations. Applications are presented for benzene and for some mesogenic molecules which constitute the principal interest of the authors. A number of properties ranging from phase stability, thermodynamic quantities, orientational order parameter and collective dynamics properties are computed and discussed.