Seminarium Fizyki Materii Skondensowanej

The role of multi-particle correlations in the appearance of aliquid–vapour critical point will be discussed. The analysis is based onBaxter’s hierarchy relating spatial integrals of (k + 1)-particlecorrelations to the k-particle ones and their derivatives with respect todensity. It turns out that the description of critical behaviour requirestaking into account correlations of arbitrary order. It is however only anecessary condition. For instance, the well known Kirkwood superpositionapproximation when applied within Baxter’s hierarchy rules out thecritical behaviour. However, the same approximation when used as a closureof the Yvon-Born-Green hierarchy still presents challenging problems. Theintriguing situation in this case will be presented in the light of bothnumerical and analytical studies together with some open problems.