Analysis of the experimental pressure-temperature behavior in the isotropic-nematic phase transition for p-azoxianisol by using different Convex Peg models

In this work, we analyzed the experimental pressure-temperature behavior in the isotropic-nematic phase transition for the liquid crystal p-azoxianisol at 1 atm by using different Convex Peg models (HERSW, HERSWS and HERSWE). Additionally, we proposed a new development for the HERSW and HERSWE models. The values of the molecular volumes of the hard and attractive cores used in these models were obtained from theoretical quantum calculations at B3LYP/6-311++G level including the solvatation model IPCM. HERSW and HERSWS models predicted adequately the I-V-N triple point. For such models, we analyzed, the case when a/b = 3.5 and λ = 3.5 (model HERSWS) and the particular cases when a/b = 3.5 and a/bλ = 1.75, a/b = 3.6 and a/bλ = 1.8 and finally, a/b = 3.7 and a/bλ = 1.85 for HERSW model. HERSWE could not predict the I-V-N triple point and it was not possible to analyze the experimental behavior. We found that the Convex Peg model HERSW with parameters a/b = 3.7 and a/bλ = 1.85 predicts quantitatively the experimental pressure-temperature behavior in the isotropic-nematic phase transition for the liquid crystal p-azoxianisol at 1 atm.