Producción Científica Profesorado

Predicting the Phase Diagram of a Liquid Crystal Using the Convex Peg Model and the Semiempirical PM3 Method



Mendoza Huizar, Luis Humberto

2002

Predicting the phase diagram of a liquid crystal using the Convex Peg model and the semi-empirical PM3 method. Eduardo García-Sánchez, Antonio Martínez-Richa, José Antonio Villegas-Gasca, Luis Humberto Mendoza-Huizar, and Alejandro Gil-Villegas. DOI: 10.1021/jp021453o


Abstract


A molecular theory to determine thermodynamic properties of isotropic and nematic phases of liquid crystals is proposed, based on a convex peg model and semiempirical PM3 (Parametrized Method 3) calculations. The Helmholtz-free energy of the molecular system, a convex hard core within an encircling spherical square-well (SW) potential, is obtained from a second-order perturbation theory for SW nonspherical particles, combined with the Parsons decoupling approximation of the translational and rotational degrees of freedom, and a long-range approximation for the evaluation of the perturbation terms. The theory is applied to predict the phase diagram and isotropic?nematic transition of p-azoxyanisole. To do this, an estimation of the volume of a p-azoxyanisole molecule is derived from a minimum-energy geometry, using PM3 calculations; the volume obtained is mapped into a hard ellipsoid revolution volume of a Convex Peg molecule. A very good agreement in the prediction of the thermodynamic properties is obtained when compared with experimental data.



Producto de Investigación




Artículos relacionados

Theoretical and Experimental Study of Cobalt Nucleation and Growth onto Gold Substrate with Differen...

Copper Electrodeposition On Glassy Carbon And Highly Oriented Pyrolytic Graphite Substrates From Per...

THEORETICAL STUDY ON THE MODIFICATION OF ACTIVE SITES IN GOLD SURFACES MODELED AS FINITE CLUSTERS: I...

Potentiometric behavior of graphite-epoxy electrochemical transducers towards anions, cations and pH...

A theoretical quantum study on the distribution of electrophilic and nucleophilic active sites on th...

Nucleation and growth of cobalt onto different substrates: Part I. Underpotential deposition onto a ...

Evaluación de Esteroides Aromáticos como Indicadores de Madurez Térmica en Extractos de Roca

Nucleation and growth of cobalt onto different substrates: Part II. The upd-opd transition onto a go...

Mercury Ions Removal from Aqueous Solution Using an Activated Composite Membrane

Cobalt electrodeposition onto highly oriented pyrolytic graphite (HOPG) electrode from ammonium sulf...