Münster 1997 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 19: Poster II

DY 19.61: Poster

Donnerstag, 20. März 1997, 09:30–12:30, Z

Perturbative density functional theory for phase transitions in a two dimensional antiferro - fluid — •P. Nielaba and S. Sengupta —
Institut für Physik, Universität Mainz, D-55099 Mainz

(S.Sengupta:) Material Science Division, IGCAR, Kalpakkam 603 102, Tamil Nadu, India
We study the temperature / density phase diagram of a fluid in two - dimensions consisting of hard discs which, in addition, possess an internal ( Ising) spin degree of freedom. The Ising spin of each disc couples with those of its neighbours via a short ranged antiferromagnetic (AF) interaction. Recent Monte Carlo simulations have shown that this system undergoes a gas -liquid transition followed by a gas - AF ordered square solid sublimation transition at low temperatures. Using a perturbative density functional approach we obtain, in addition to the observed transitions, a freezing transition at high density to a frustrated triangular solid phase. Interestingly, the calculated phase diagram suggests that at low temperatures, this transition is suppressed so that over a range of parameters, the system refuses to crystallize.

[1] P.Nielaba, S. Sengupta, Phys. Rev. E (in press)