Role of the reference system in study of fluid criticality by effective LGW Hamiltonian approach

Statistical field theory of ion-molecular solutions

“…The field-theoretic (FT) methods based on the Hubbard-Stratonovich (HS) integral transformation of the configuration integral and correlation functions of a certain model fluid in the form of a functional integral over one or few space-dependent fluctuating fields could become such a tool. At present, these methods are well-proven as the ones for describing the thermodynamic and structural properties of simple neutral and ionic fluids [20][21][22][23][24][25][26][27][28][29][30][31][32] and polymer solutions 33,34 . Among them are the mean-field (saddlepoint) approximation 30,32,35,36 , random-phase approximation 33,37,38 , many-loop expansion 39 , variation method 40 , and the renormalization group theory 41 .…”

$ϕ^4$ Theory Hamiltonian for Fluids: Application to the surface tension near the critical point

“…These studies of the fluid criticality by means of the LGW Hamiltonian approach were performed for the case of the hard spheres reference system. Recently, the case when the reference system in addition to the hard-sphere repulsion includes also the short range attraction was considered in [11]. Still, it was not explicitly demonstrated that the effective LGW Hamiltonian with its coefficients expressed in terms of the known properties of the reference system, is equivalent to the Hamiltonian of the φ 4 field theory model.…”