title: Molecular dynamics simulation study on the isomerization and molecular orientation of liquid crystals formed by azobenzene and (1-cyclohexenyl)phenyldiazene.
abstract: Atomistic molecular dynamics simulations have are used to investigate the liquid crystal systems based on [4-pentyl-(1-cyclohexenyl)]-(4-cyanophenyl)diazene (5CPDCN) and 4-cyano-4'-pentylazobenzene (5AZCN). The results show the growth process of a nematic phase from a disordered phase. Then the phase transition caused by isomerization reaction is studied based on a temporary modification of the dihedral potential. The properties of 5AZCN and 5CPDCN are compared, showing that the orientation of trans-5CPDCN is more highly ordered than trans-5AZCN. This can be attributed to the more extended dihedral angles φ(2) (i.e. the dihedral angle between the ring system and the terminal chain) in trans-5CPDCN enhance the rod-like conformation of the molecules. The orientational correlation functions g(l)(r) (l = 1, 2) are also calculated, by which we find that both 5CPDCN and 5AZCN systems in nematic phase present parallel and anti-parallel dipole correlations. The anti-parallel dipole correlation is localized for the 5CPDCN system; on the contrary, the parallel dipole correlation is weakly localized for the 5AZCN system.
authors.affiliation: State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China.
authors.forename: Xiang-Gui
authors.initials: XG
authors.lastname: Xue
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.forename: Zhong-Yuan
authors.initials: ZY
authors.lastname: Lu
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Li
authors.forename: Ze-Sheng
authors.initials: ZS
authors.lastname: Li