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Lattice models of ionic systems

2002; American Institute of Physics; Volume: 116; Issue: 17 Linguagem: Inglês

10.1063/1.1464827

1520-9032

Vladimir Kobelev, Anatoly B. Kolomeisky, Michael E. Fisher,

Spectroscopy and Quantum Chemical Studies

A theoretical analysis of Coulomb systems on lattices in general dimensions is presented. The thermodynamics is developed using Debye-Huckel theory with ion-pairing and dipole-ion solvation, specific calculations being performed for 3D lattices. As for continuum electrolytes, low-density results for sc, bcc and fcc lattices indicate the existence of gas-liquid phase separation. The predicted critical densities have values comparable to those of continuum ionic systems, while the critical temperatures are 60-70% higher. However, when the possibility of sublattice ordering as well as Debye screening is taken into account systematically, order-disorder transitions and a tricritical point are found on sc and bcc lattices, and gas-liquid coexistence is suppressed. Our results agree with recent Monte Carlo simulations of lattice electrolytes.