Bad Gastein, January 2005 Gels and Strong Liquids In collaboration with S. Bulderyev,C. De Michele, E. La Nave, A. Moreno, I. Saika-Voivod, P. Tartaglia, E. Zaccarelli titolo

Strong-fragile: Dire Stretched, Delta Cp Hard Sphere Colloids: model for fragile liquids

Geometric Constraint: Maximum Valency SW if # of bonded particles <= N max HS if # of bonded particles > N max V(r) r Maximum Valency

Phase Diagram

Visual

Viscosity and Diffusivity: Arrhenius  =1  C v small Stokes-Einstein Relation Other strong properties: percolating

Energy per Particle Ground State Energy Known ! It is possible to equilibrate at low T ! E(T) is known and hence free energy can be calculated exactly down to T=0

It is possible to calculate exactly the vibrational entropy of one single bonding pattern (basin free energy) Basin Free energy (Ladd and Frenkel)

Thermodynamics in the Stillinger-Weber formalism F(T)=-T S conf (E(T))+f basin (E,T) with F basin (E) and S conf (E)=k B ln[  (E)] Sampled Space with E bonds Number of configurations with E bonds Stillinger-Weber

sconf Comment: In models for fragile liquids, the number of configurations with energy E has been found to be gaussian distributed Non zero ground state entropy

Landscape of strong and fragile liquids Realistic Model Network Primitive Model for Network Fragile Liquid

Silica Primitive Model From models for gels to models for network forming liquid Si O

Points for discussions…. Sticky points colloids: Candidates for Gel formations by suppression of the spinodal decomposition Candidates for strong liquid behavior. Landscape differences between strong and fragile liquids. Is the configurational entropy of strong liquids at low T (in the classical limit) non zero Proteins: Sticky areas. Gel if favored. Role of the space correlation between the points. No crystals for special sticky points configurations ?

N MAX -modified Phase Diagram Phase Diagram