Session Q1 - Materials Modeling IV.
MIXED session, Wednesday afternoon, August 27
Room 1, Classroom Unit
We describe large-scale simulation studies of a recently reported(W.R.\ Folks, Yu A.\ Reznikov, S.N.\ Yarmolenko, O.D.\ Lavrentovich, Mol.\ Cryst.\ Liq.\ Cryst.\ 292), 183 (1997). low-power opto-optical effect in the Sm A phase of a cyanobiphenyl compound (8CB) doped with photosensitive molecules (7AB), in which irradiation by a 1-10 mW He-Ne laser beam leads to layer undulations and strongly scattering textures. This effect could be used to store data, with the written information erased by another beam with different wavelength (e.g.\ by an Ar laser), and is thought to involve layer shrinkage caused by light-induced transformation (trans-cis isomerization) of the 7AB molecules. We present results obtained for pure 8CB in the isotropic, nematic and Sm A phases, and for 8CB/7AB mixtures in the Sm A phase. Thermodynamic, structural, and dynamical properties of neat 8CB are computed and compared with experiment, and two simulations of 8CB/7AB mixtures, one with all 7AB molecules in the trans conformation and the other with all 7AB molecules in the cis conformation, are discussed in light of the proposed instability mechanism.