Almarza, N. G.Lomba, EnriqueRuiz, GuiomarFernández Tejero, Carlos2023-06-202023-06-202001-03-050031-900710.1103/PhysRevLett.86.2038https://hdl.handle.net/20.500.14352/58869© 2001 The American Physical Society. We acknowledge financial support from the Dirección General de Enseñanza Superior e Investigación Científica (DGESCYT) under Grants No. PB98-0673-C02-02 (N.G. A.), No. PB97-0258-C02-02 (E. L.), and No. PB97-0004-C03-03 (G. R. and C. F. T.).Evidence of a liquid-liquid equilibrium in simple fluids has recently been exposed for a density-dependent pair potential in the framework of a van der Waals theory. Here this double criticality is investigated by means of computer simulation, a perturbation theory, and integral equation theory. It is found that the critical point estimated from the integral equation thermodynamics is not associated with divergent correlations. To cope with these features, a special simulation procedure, based on the definition of local densities, is devised. Monte Carlo calculations confirm the existence of two critical points, in agreement with the predictions of perturbation theory.engjournal articlehttp://dx.doi.org/10.1103/PhysRevLett.86.2038http://prl.aps.org/restricted access536Attractive forcesPhase-diagramTermodinámica2213 Termodinámica