title: Vapor-liquid transitions of dipolar fluids in disordered porous media: performance of angle-averaged potentials.
abstract: Using replica integral equations in the reference hypernetted-chain (RHNC) approximation we calculate vapor-liquid spinodals, chemical potentials, and compressibilities of fluids with angle-averaged dipolar interactions adsorbed to various disordered porous media. Comparison with previous RHNC results for systems with true angle-dependent Stockmayer (dipolar plus Lennard-Jones) interactions indicate that, for a dilute hard sphere matrix, the angle-averaged fluid-fluid (ff) potential is a reasonable alternative for reduced fluid dipole moments m( *2)=mu(2)/(epsilon(0)sigma(3))< or =2.0. This range is comparable to that estimated in bulk fluids, for which RHNC results are presented as well. Finally, results for weakly polar matrices suggest that angle-averaged fluid-matrix (fm) interactions can reproduce main features observed for true dipolar (fm) interactions such as the shift of the vapor-liquid spinodals towards lower temperatures and higher densities. However, the effective attraction induced by dipolar (fm) interaction is underestimated rather than overestimated as in the case of angle-averaged ff interactions.
authors.affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Sekretariat TC7, Technische Universität Berlin, Strasse des 17, Juni 124, D-10623 Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Spöler
authors.forename: S H L
authors.initials: SH
authors.lastname: Klapp