Hostname: page-component-7b7567c8c-2n9c9 Total loading time: 0 Render date: 2026-11-14T23:18:34.146Z Has data issue: false hasContentIssue false
  • English
  • Français

Molecular Dynamics Simulation Of A Cyclic Siloxane Based Liquid Crystalline Material

Published online by Cambridge University Press:  16 February 2011

Soumya S. Patnaik,
Ruth Pachter,
Steve Plimpton and
W. WADE ADAMS
Soumya S. Patnaik
Affiliation:
University of Virginia. Mailing address: WL/MLPJ, Wright-Patterson AFB, OH 45433
Ruth Pachter
Affiliation:
WL/MLPJ, Wright-Patterson AFB, OH 45433
Steve Plimpton
Affiliation:
Dept. 1421, Sandia National Laboratories, Albuquerque, NM 87185
W. WADE ADAMS
Affiliation:
WL/MLPJ, Wright-Patterson AFB, OH 45433
Get access

Abstract

We have used molecular dynamics (MD) to study the room temperature bulk phase behavior of a cyclic siloxane with a pentamethylcyclosiloxane core and biphenyl-4-allyloxybenzoate Mesogens (BCS). This Material exhibits thermotropic liquid crystalline behavior above 120 °C. Bonded and non-bonded interactions were considered and a Molecular Mechanics force field was used to model the structural anisotropy of the siloxane Molecules. Molecular clusters with and without periodic boundary conditions (pbc) were studied to investigate the effect of the finite system size on the time evolution of the molecular structure. The precise nature of the boundary conditions was found to be significant and simulations that exclude pbc were better able to model the molecular system. It was found that molecular shapes associated with low energy conformations were not cylindrically symmetric but more splayed like. An approximate measure of the shape of the mesogens was obtained by describing ellipsoids around the Mesogens, and estimating the molecular length, breadth, and width from the principal axes of the ellipsoids. The orientational order was then calculated by defining the molecular axis to be along the major principal axis.

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

REFERENCES

1. Bunning, T.J., McNamee, S.G., McHugh, C.M., Patnaik, S.S., Ober, C.K., and Adams, W.W. in Applications of Synchrotron Radiation Techniques to Materials Science, edited by Perry, D.L., Shinn, N.D., Stockbauer, R.L., D'Amico, K.L. and Terminello, L.J. (Mater. Res. Soc. Proc. 307, Pittsburgh, PA, 1993) pp. 311–316.Google Scholar
2. Patnaik, S.S., Pachter, R., Bunning, T.J., Crane, R.L. and Adams, W.W., to appear in Liquid Crystals.Google Scholar
3. Allen, M.P., Frenkel, D. and Talbot, J., Computer Physics Reports 9, 301 (1989).CrossRefGoogle Scholar
4. Frenkel, D. in Phase Transitions in Liquid Crystals, edited by Martelluci, S. and Chester, A.N. (Plenum Press, New York, 1992) p.67.CrossRefGoogle Scholar
5. Eppenga, R. and Frenkel, D., Mol. Phys. 52 (6), 1303 (1984).CrossRefGoogle Scholar
6. Wilson, M.R. and Allen, M.P., Mol. Cryst. Liq. Cryst., 198, 465 (1991).CrossRefGoogle Scholar
7. Wilson, M.R. and Allen, M.P., Liq. Cryst. 12 (1), 157 (1992).CrossRefGoogle Scholar
8. Plimpton, S.J., Hendrickson, B.A., and Heffelfinger, G.S. in Proceedings of 6th SIAM Conference on Parallel Processing for Scientific Computing, (SIAM, Philadelphia, PA, 1993) p.178.Google Scholar
9. Brooks, B.R., Bruccoleri, R.E., Olafson, B.D., States, D.J., Swaminathan, S. and Karplus, M., J. of Comp. Chem. 4 (2), 187 (1993).CrossRefGoogle Scholar
10. QUANTA is a Molecular Modeling package developed by Molecular Simulation Inc., Waltham, MA 02154. The parameters of version 2.2 (1993) were used.Google Scholar
11. Ober, C.K., McNamee, S.G., McHugh, C.M., Bunning, T.J., Patnaik, S.S. and Adams, W.W., presented at the APS March Meeting, Seattle, WA, 1993 (unpublished).Google Scholar