Computer rendered picture showing the disordered hydrogen bonding network typical of liquid water. The blue spheres are oxygen and the white spheres are hydrogen. The dotted lines show the hydrogen bonds with which the water molecules attract one another. In the presence of large hydrophobic solute, the hydrogen bond network is necessarily disrupted. This would lead to the depletion of hydrogen bonding and drying near extended surfaces. Professor Chandler and his group have studied the necessary conditions and the implications of this phenomenon.

(Click here for a version of our ideas on hydrophobicity.)

Schematic representation of the rugged potential energy surface of a complex system. Such a system has, in effect, an uncountable number of features, only a vanishingly small fraction of which are pertinent to dynamics carrying the system from one long-lived basin to another. Understanding rare transitions occurring in such a system, for instance chemical reactions in solution, poses the problem of finding and analyzing the trajectories that move on such a surface. As the picture illustrates, there are many (possibly torturous) pathways. A representative sampling of important routes is required. Together with postdoctorals and students Peter Bolhuis, Christoph Dellago, Phillip Geissler, Gavin Crooks, Felix Csajka and Ka Lum, Professor Chandler has developed a systematic approach to find these trajectories with the help of computer simulations.

(Click here for a description of the Transition Path Sampling method.)

Working with Juan P. Garrahan, Professor Chandler has created a microscopic theory of glass formers. Their theory (solid lines) is compared with experiment for relaxation times and viscosity as functions of temperature for various glass forming liquids [PDF]. GeO₂ is a so-called "strong" glass former as it obeys Arrhenius temperature dependence. 3BP (i.e., 3-bromopentane) and OTP (i.e., ortho-terphenyl) are so-called "fragile" glass formers as they exhibit super-Arrhenius temperature dependence over the range of experimentally accessible conditions. Garrahan and Chandler have shown that in general, there is a crossover behavior between fragile and strong behaviors. APOC (alpha-phenyl-ortho-cresol) and SL (salol) exhibit this crossover, as made explicit by the blue and red dashed lines showing fragile and strong behaviors, respectively.

(Please click here for more about this work.)

How is it that 60 proteins (a few of which are depicted at the left) reliably assemble to form the ordered capsid of the alfalfa mosaic virus capsid (depicted center and right)? It is an important question for both structural biology and nano-scale materials science. Addressing this question with trajectory studies of several models of capsid-forming proteins, Michael Hagan and Professor Chandler have concluded that successful assembly is a non-equilibrium phenomenon where kinetics trumps thermodynamic stability, and further, it is an example of order-disorder phenomena in space-time.

To learn more about their work on this topic, click here.