Michael Cohen

I have investigated the quantum mechanics of liquid helium, calculating properties of the bulk fluid as well as the surface (density profile and surface excitations).

I am interested in applying statistical mechanics to the analysis of simple models of real-world systems. An analysis of a simple model of displacive ferroelectrics led to an interesting phase diagram and an understanding of mode softening as the precursor of a displacive transition. With a biologically-oriented coworker, I have studied the equilibrium between a membrane (wilh sites which can adsorb molecules) and a fluid containing those molecules. We have studied fairly complicated membranes, taking account of the geometrical competition for sites and also including electrostalic effecls in a mean-field approximation.

Classical electromagnetic theory has always engaged me. At present I am studying a model of growth processes ("diffusion limited aggregation"), some aspects of which are exactly described by the mathematics of electrostatics.

• Prof. Emeritus
• Postdoctoral positions al CalTech and the Institute for Advanced Study (Princeton)

• (with T.J. Einstein), "Statistical Mechanics of a Simple Model of a Displacive Ferroelectric," Phys. Rev. B, 7, 1932 (1973).
• (with C.C. Chang), "Microscopic Theory of Surface Excitations in Superfluid Hel," Phys. Rev. B 11, 1059 (1975).
• (with J.A. Cohen), "Adsorption of Monovalent and Divalent Cations by Phospholipid Membranes: the Monomer-Dimer Problem," Biophys. Journal 36, 623 (1981).
• (with A.B. Harris), "Scaling of Negative Moments of the Growth Probability of Diffusion Limited Aggregates" (in press), Phys. Rev. A41, 971 (1990