All Physics Faculty Presentations


Extended BEG Model of Halogenated Methanes physisorbed on ionic crystals

Document Type

Conference Paper

Journal/Book Title/Conference

Bulletin of the American Physical Society



Publication Date



The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the BEG approximation, using a mean-field approximation, where the interaction parameters are related to system interaction energies using a unique averaging procedure. The model is applied to halogenated methanes physisorbed on MgO(100) and NaCl(100) using previous experimental and theoretical studies to determine the interaction energies. We find temperature-dependent antiferroeletric to ferroelectric dipole phase transitions and order-disorder phase transitions can occur. Phase diagrams are presented.


Bull. Am. Phys. Soc. 46(1) Part II, 848, (2001). American Physical Society March Meeting 2001, March 12 - 16, 2001, Seattle, Washington.