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A Molecular Dynamics Study of the Effect of Steric Properties on the Melting of Quasi Two-Dimensional Systems

  • Flemming Y. Hansen
  • H. Taub
Part of the NATO ASI Series book series (NSSB, volume 267)

Abstract

The effect of molecular steric properties on the melting of quasi two-dimensional solids is investigated by comparing molecular dynamics simulations of the melting of butane and hexane monolayers adsorbed on the graphite (002) surface. These molecules differ only in their length, being members of the n-alkane series [CH3(CH2)nCH3], where n=2 for butane and n=4 for hexane and have similar solid monolayer structures on graphite. The simulations show a qualitatively different melting behavior for the butane and hexane monolayers consistent with neutron and x ray scattering experiments. The melting of the low-temperature herringbone (hb) phase of the butane monolayer is abrupt and characterized by a simultaneous breakdown of translational order and orientational order of the molecules about the surface normal. In contrast, the hexane monolayer exhibits polymorphism in that the solid (hb) phase transforms to a rectangular centered (rc) structure with a short coherence length in coexistence with a fluid phase. The formation of gauche molecules is essential for the melting process in the hexane monolayer but unimportant for butane. A mechanism for the melting of the (hb) phase is proposed. It is based on vacancy creation within the monolayer by molecules reducing their “footprint” on the surface either by a conformation change, tilting with respect to the surface, or promotion to a second layer.

Keywords

Melting Behavior Orientational Order Vacancy Formation Bend Angle Mono Layer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    J.M. Kosterlitz and D.J. Thouless, J. Phys. C 6, 1181 (1973).ADSCrossRefGoogle Scholar
  2. 2.
    B.I. Halperin and D.R. Nelson, Phys. Rev. Lett. 41, 121 (1978).MathSciNetADSCrossRefGoogle Scholar
  3. 3.
    D.R. Nelson and B.I. Halperin, Phys. Rev. B 19, 2457 (1979).ADSCrossRefGoogle Scholar
  4. 4.
    A.P. Young, Phys. Rev. B 19, 1855 (1979).ADSCrossRefGoogle Scholar
  5. 5.
    N.D. Mermin and H. Wagner, Phys. Rev. Lett. 17, 1133 (1966).ADSCrossRefGoogle Scholar
  6. 6.
    K.J. Strandburg, Rev. Mod. Phys. 60, 161 (1988) and references therein.Google Scholar
  7. 7.
    H.K. Kim, Q.M. Zhang and M.H.W. Chan, Phys. Rev. Lett. 56, 1579 (1986).ADSCrossRefGoogle Scholar
  8. 8.
    J.Z. Larese, L. Passell, A.D. Heidemann, D. Richter and J.P. Wickstedt, Phys. Rev. Lett. 61, 432 (1988).ADSCrossRefGoogle Scholar
  9. 9.
    S. Zhang and A.D. Migone, Phys. Rev. B 38, 12039 (1988).ADSCrossRefGoogle Scholar
  10. 10.
    F.F. Abraham, Phys. Rev. B 28, 7338 (1983).ADSCrossRefGoogle Scholar
  11. 11.
    F.F. Abraham, Phys. Rev. Lett. 50, 978 (1983).MathSciNetADSCrossRefGoogle Scholar
  12. 12.
    F.F. Abraham, Phys. Rev. B 29, 2606 (1984).Google Scholar
  13. 13.
    S.W. Koch and F.F. Abraham, Phys. Rev. B 27, 2964 (1983).ADSCrossRefGoogle Scholar
  14. 14.
    H. Taub, in The Time Domain in Surface and Structural Dynamics, edited by G.J. Long and F. Grandjean, NATO Advanced Study Institute Series C, Vol. 228 ( Kluwer, Dordrecht, 1988 ), p. 467.Google Scholar
  15. 15.
    S. Leggetter and D.J. Tildesley, Berichte der Bunsen Gesellschaft für Physikalische Chemie 94, 285 (1990).Google Scholar
  16. 16.
    J.C. Newton, Ph.D thesis, University of Missouri-Columbia USA (1989).Google Scholar
  17. 17.
    F.Y. Hansen J.C. Newton and H. Taub, unpublished.Google Scholar
  18. 18.
    J.P. Ryckaert, G. Cicotti, and H.J.C. Berendsen, J. Comp. Phys. 23, 327 (1977).ADSCrossRefGoogle Scholar
  19. 19.
    T.A. Weber, J. Chem. Phys. 69, 2347 (1978).ADSCrossRefGoogle Scholar
  20. 20.
    T.A. Weber, J. Chem. Phys. 70, 4277 (1979).ADSCrossRefGoogle Scholar
  21. 21.
    W.A. Steele, The interaction of gases with Solid Surfaces ( Pergamon Press, London 1974 ).Google Scholar
  22. 22.
    M. Pear and J.H. Weiner, J. Chem. Phys. 71, 212 (1979).ADSCrossRefGoogle Scholar
  23. 23.
    H.D. Stidham and J.R. Durig, Spectrochimica Acta 42A, 105 (1986).CrossRefGoogle Scholar
  24. 24.
    K. Raghavachari, J. Chem. Phys., 81, 1383 (1984).ADSCrossRefGoogle Scholar
  25. 25.
    F.Y. Hansen, unpublished.Google Scholar
  26. 26.
    F.Y. Hansen and H. Taub, unpublished.Google Scholar
  27. 27.
    F.Y. Hansen, unpublished.Google Scholar
  28. 28.
    P. Dai, H. Taub, T.O. Brun, F. Trouw, and F.Y. Hansen, unpublished.Google Scholar

Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • Flemming Y. Hansen
    • 1
  • H. Taub
    • 2
  1. 1.Fysisk-Kemisk InstitutThe Technical University of DenmarkLyngbyDenmark
  2. 2.Department of Physics and AstronomyUniversity of MissouriColumbiaUSA

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