Condensed Matter Physics, 2015, vol. 18, No. 2, 24601
DOI:10.5488/CMP.18.24601           arXiv:1504.06153

Title: Gas-liquid critical point of the ultrasoft restricted primitive model from analytic theory
  O. Patsahan (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine)

Gas-liquid criticality in the ultrasoft restricted primitive model (URPM) of polyelectrolytes is studied using the collective variables-based theory. For the model, an effective Hamiltonian is derived and explicit expressions for all the coefficients are found in a one-loop approximation. Based on this Hamiltonian, the phase and critical behaviour is analysed. Our results provide evidence that the nature of the gas-liquid criticality in the URPM is the same as in the restricted primitive model that includes a hard core.

Key words: polyelectrolytes, ultrasoft restricted primitive model, gas-liquid critical point, effective Hamiltonian
PACS: 64.75.-g, 64.60.De, 64.75.Cd, 64.60.fd

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