Liquid-liquid phase transition for an attractive isotropic potential with wide repulsive range.
We investigate how the phase diagram of a repulsive soft-core attractive potential, with a liquid-liquid phase transition in addition to the standard gas-liquid phase transition, changes by varying the parameters of the potential. We extend our previous work on short soft-core ranges to the case of large soft-core ranges, by using an integral equation approach in the hypernetted-chain approximation. We show, using a modified van der Waals equation we recently introduced, that if there is a balance between the attractive and repulsive part of the potential this potential has two fluid-fluid critical points well separated in temperature and in density. This implies that for the repulsive (attractive) energy U(R)(U(A)) and the repulsive (attractive) range w(R)(w(A)) the relation U(R)/U(A) proportional to w(R)/w(A) holds for short soft-core ranges, while U(R)/U(A) proportional to 3w(R)/w(A) holds for large soft-core ranges.
Malescio
Gianpietro
G
Dipartimento di Fisica, Università di Messina and Istituto Nazionale Fisica della Materia, 98166 Messina, Italy.
Franzese
Giancarlo
G
Skibinsky
Anna
A
Buldyrev
Sergey V
SV
Stanley
H Eugene
HE