15 February 2012, 2.15 pm
School of Physics, Rm 3.34
Theoretical Physics, School of Physics, UoB
Classical statistical mechanics determines the average properties of condensed matter starting from a description in terms of atoms (or molecules or ions) and the forces between these. More generally one begins with an effective Hamiltonian where higher energy, e.g. electronic, degrees of freedom have been integrated out. Whilst the properties of homogeneous phases, i.e. bulk solids, liquids and gases and the transitions between these, are rather well-understood - at least for systems where the interatomic forces are simple, this is not the case when interfaces and surfaces are present. Inhomogeneities in density arise from the breaking of translational invariance and a variety of new interfacial phenomena occur which have no direct counterpart in bulk. These include i)adsorbed fluid films at solid substrates where wetting and layering phase transitions can occur, ii) the structure and phase equilibria of fluids in narrow pores or capillaries, or confined between plates as in the Surface Force Apparatus (SFA) or between a tip and a substrate as in the Atomic Force Microscope (AFM), where finite-size effects and substrate-fluid forces makes the properties of the confined system very different from those in bulk, iii) the nucleation of liquid droplets and gas bubbles and iv) the statistical mechanics of small systems as exemplified by small cavities containing, typically, 2-100 atoms, relevant in nanoscience. Understanding the solvation of a large solute particle in a solvent, germane to physical chemistry, is another challenging problem in the statistical mechanics of inhomogeneous fluids.