Transferability of first principles derived torsional potentials for mesogenic molecules and fragments

Abstract

The transferability of torsional potentials governing molecular flexibility is investigated using first principles density functional calculations. We aim to define the criteria required for transferability between different molecular systems and to quantify the mechanisms which reduce it. We begin by examining the influence that polar and lateral substituents have on the torsional potentials for the liquid crystal molecular fragments, biphenyl and phenyl cyclohexane. We also determine the flexibility of alkyl and alkoxy tail groups attached to both benzene and cyclohexane units. For the systems investigated, we find that the transferability depends sensitively on steric factors and molecular electronic structure particularly through the degree of electron delocalization and dipolar interactions. Finally, we explore the transferability of fragment-derived potentials to liquid crystal forming molecules, by examining the coupling between the inter-ring torsion and flexible alkyl tail for the liquid crystal molecule 4-n-pentyl-4′-cyanobiphenyl (5CB).

Notes

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