Incommensurate solids, that is those solids which possess some aperiodic structure which does not reflect the fundamental periodicity of the parent crystal structure, pose another very interesting class of problems. Since the natural periodicity of the physisorbed monolayer solid is usually different from that of the crystalline surface on which it lies, monolayer systems often form incommensurate structures due to the competing forces of the intra-monolayer interactions and the interactions of the monolayer with the surface.
Sometimes the periodicity of the parent crystal can be
partially recovered, and this leads to the so-called commensurate phases.
This part of the research program is focused on the study of the structure
of both the commensurate and incommensurate phases and of the phase transitions
between them.
One of the more interesting problems in condensed matter
physics is that of the melting of a solid in two dimensions. The main question
is whether the melting occurs through a discontinuous transition as it
does in bulk (three-dimensional) systems, or whether this melting occurs
via a continuous transition, very different from bulk systems. This problem
has been one of great interest for many years. One approach to this problem
is through computer simulations and this is work that has involved a number
of undergraduate students.
This page is maintained by Anthony D. Novaco