Field-induced alignment of the directors in the smectic A phase. Experiment and simulation

In contrast to nematics far less is known about the alignment of the direct ors in a smectic A phase by an external field. To characterise this process , which necessarily involves the flow of the molecules, we have undertaken an NMR investigation of the smectic A phase of 4-octyl-4'-cyanobiphenyl. Th e results of these experiments have revealed that, as expected, the alignme nt of the directors is a complex process strongly influenced by the nature of the containing surface for the smectic A phase. To assist in understandi ng the alignment process we have used computer simulations to study the fie ld induced alignment of the directors in the smectic A phase formed by the Gay-Berne mesogen GB(4.4,20.0,1.1).