A dissipative particle dynamics study of the realignment of a nanodroplet of a nematic in a weak external magnetic field
Section for Computational Biophysics, Department of Physics and Astronomy, Ornstein Laboratory, P.O. Box 80.000, 3508 TA, Utrecht, The Netherlands
2 Dipartimento di Scienze Chimiche, Università di Padova, Via Loredan 2, 35131, Padova, Italy
Accepted: 20 April 2007
Published online: 14 May 2007
We present a dissipative particle dynamics (DPD) approach for simulating the realignment of a nematic nanodroplet suspended in an isotropic fluid following a switch in the direction of an applied external magnetic field. The interaction of the mesogens with the external field is weak relative to the inter-molecular interactions. The simulations were used to investigate the way orientational equilibrium is re-established. The results reveal that the realignment process of the nanodroplet is consistent with its fluid structure. The reorientation of the nanodroplet as a whole is found to be caused by an internal structural rearrangement rather than a coherent rotation of the centres of mass of the mesogens about the centre of the nanodroplet. The switch in the field direction furthermore is found to induce a transient spatial variation in the orientational order of the long axes of the mesogens: the orientational order parameters decreases on moving from the core of the nanodroplet to the surface in contact with the isotropic environment. The results highlight differences between the time evolution of the orientation of the long molecular axes in the field and the rotations of the centres of mass of the mesogens about the centre of the nanodroplet.
PACS: 61.30.Cz Molecular and microscopic models and theories of liquid crystal structure – / 61.43.Bn Structural modeling: serial-addition models, computer simulation –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2007