Prof. Per Linse: Cause and control of order in dipolar fluids
Source: Monday physics colloquium
Cause and control of order in dipolar fluids
Prof. Per Linse, Division of Physical Chemistry, Lund University, Sweden
The first attempt to understand the dielectric behavior of molecular media dates back to the middle of the 19th century and the work of Clausius and Mossotti. They developed independently the well-known Clausius-Mossotti equation. Later, in the first half of the 20th century, Langevin, Onsager, and Kirkwood made important contributions to our understanding of the dielectric behavior of a molecular fluid. In the 70ies of the last century, Niehuis and Deutch and somewhat later Wertheim further developed our understanding of these systems.
Though, investigations of the dielectric behavior of molecular media have been the subject for over 150 years; yet a deep understanding of the many-body phenomena that give rise to the collective dipolar polarization is still incomplete. Such an understanding of the relation between the molecular properties and interactions, on one hand, and the spontaneous and fluctuating polarization, on the other hand, is of central importance (i) to rationalize the solvation of ions in media and manipulate properties of solvent molecules to achieve desired dielectric properties and (ii) to relate orientational correlations of particles with their structure and dipole moment with the goal to fabricate particles with more complex non-central forces.
My presentation deals with some additional steps[1,2] to unravel the fascinating field of dipole polarization from simulation of simple models using penalty functions and by controlled changes of molecular shape and by introducing higher order electrostatic moments.
 Karlström and Linse, J. Stat. Phys., 2011, 145, 410-417 Linse and Karlström, J. Stat. Phys., 2011, 145, 418-440