CONDENSED MATTER AND STATISTICAL PHYSICS SECTION INFORMAL SEMINAR on Statistical Physics

[CM ICTP - Trieste]

CONDENSED MATTER AND STATISTICAL PHYSICS SECTION

	
INFORMAL SEMINAR  on  Statistical Physics





Wednesday, 18 July    -    11:00 a.m.



Seminar Room - Main Building 1st Floor


		


D. DHAR
( Tata Institute of Fundamental Research, Mumbai )



" Orientational ordering of
hard  long rods on a lattice "



Abstract
The study of systems hard rods has a long history. In 1949, Onsager 
argued that a system of hard rod-like molecules in solution with only 
excluded volume interaction would show long-range orientational order 
for high solvent densities. The existence of an orientationally ordered 
phase in the case of lattice models of straight hard rods of length k 
has remained controversial so far. Only the case k=2 is analytically 
soluble.
We argue that a system of straight rigid rods of length k on square 
lattice with only hard-core interactions shows two phase transitions as 
a function of density ρ for k ≥ 7. There is a phase transition from the 
low-density disordered phase to a nematic phase as ρ is increased from 
0 at ρ = ρc1, and there is a second phase transition from the nematic 
phase to a disordered phase at ρ = ρc2 <1.