Two dimensional systems

Some physical systems are best treated in two dimensions. Adsorption of atomic or diatomic monolayers onto smooth surfaces or monoatomic or diatomic molecules intercaleted between layers of a 2-D network material like graphite are such systems. Interestingly, some fundamental problems like binary or ternary alloys, phase behavior of binary fluids are suitably studied in two dimensions.

Graphite Intercalation Compounds

Our studies included structural and dynamical behavior of screened coulomb systems and stage-2 alkali metal intercalated graphite.(1-8)

Two Dimensional Colloids

Recently, Kusner et al. [Phys. Rev. Lett. 73, 3113 (1994); Phys. Rev. B 49, 9190 (1994); ibid 51, 5746 (1995)] have experimentally studied a 2-D colloidal lattice of about 10^4 monodispersed polystyrene latex spheres with sulfonate surface groups in water confined between two parallel glass plates while being subjected to a strong perpendicular ac field. This system effectively exhibits 1/r^3 interaction among the latex spheres and exhibits a distinct hexatic phase which can be directly imaged. We report extensive Molecular Dynamics simulations on a model system which incorporates the crucial features of the experimental system of Kusner et al. in a 10^4 particle lattice. Our studies indicate the possible existence of a hexatic phase at which the orientational correlation function C_6(r) ~ r^(-\eta_6(T)), with \eta_6 ~ 1/4 at the hexatic to liquid transition point.

References

  1. S.D. Mahanti, H. Seong, S. Sen and T. Cagin, "Structure, melting and dynamics of screened coulomb systems in 2-D: Role of corrugation," Mol. Cryst. Liq. Cryst. 244, A141 (1994);
  2. T. Cagin, S. Sen, H. Seong and S.D. Mahanti, "Ionic overlayers on corrugated surfaces: Structure," Materials Theory and Modeling, pp 233-7, 1993.
  3. H. Seong, S.D. Mahanti, S. Sen, and T. Cagin, "Ionic overlayers on corrugated surfaces: Melting," Materials Theory and Modeling, pp 297-301, 1993.
  4. T. Cagin, S. Sen, H. Seong and S.D. Mahanti, "Structural properties of stage 2 alkali graphite intercalation compounds," Molec. Simuln. 10, 41 (1993)
  5. H. Seong, S. Sen, S.D. Mahanti and T. Cagin, "Melting of a repulsive screened coulomb system in 2-D: Effect of corrugation," Phys. Rev. B 46, 8748 (1992);
  6. H. Seong, S. Sen, T. Cagin and S.D. Mahanti, "Domains and domain walls in graphite intercalation compounds," Phys. Rev. B 45, 8841 (1992);
  7. S. Sen, T. Cagin, H. Seong and S. D. Mahanti, in Recent Developments in Computer Simulation Studies in Condensed Matter Physics IV ed. D. P. Landau etal (Springer Verlag) 1991.
  8. Z. M. Chen, T. Cagin and B. M. Pettitt, unpublished.
  9. T. Cagin and S. Sen, unpublished.

Collaborators

Drs. H. Seong, Z. M. Chen and Profs. S.D. Mahanti, S. Sen and B. M. Pettitt.
tahir@wag.caltech.edu