The vapor-liquid criticality of a fluid of charged hard dumbells is investigated empolying grand canonical Monte Carlo simulations and mixed-field finite-size scaling methods.The reduced critical temperature and density obtained are T~*_c=0.04911+-0.00003 and rho~*_c=0.101+-0.003,respectively.The crtical temperature is very close to that of the resricted primitive model(RPM) for ionic fluids,while the critical density is approx 25% larger than that of the RPM.The "fits" to the Ising ordering operator distribution are good,and are of similar quality to those found for the RPM with systems operator distribution are good,and are of similar quality to those found for the RPM with systems of comparable size.however,for the finite-sizesystems simulated,the constant volume heat capacity,C_V gives no indication of an Ising-type"divergence"at T_c.This is analogous to the RPM,and serves to demonstrate that this still puzzling behavior is not restricted to that model.
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