Rapid computational prediction of crystalline polymorphism

•  The ability of an
  organic molecular solid to crystallize into different structures is  a phenomenon known as polymorphism.
•  Polymorphism is an
  issue of major concern in the pharmaceutical industry.  In many drug compounds, some fraction
  of the crystal structures that can be formed cause the drug to lose its
  therapeutic function.  If these
  structures are not known at the time of the drug’s release onto the market,
  they can turn up unexpectedly in the manufacturing process with potentially
  serious consequences.
•  We have developed a computational technique capable of
  rapidly identifying these different crystalline forms. The method supplements
  molecular dynamics with an algorithm for smoothly evolving the parameters of
  the crystalline unit cell (right figure), thereby driving the molecules in the
  unit cell from one crystal structure to another in a calculation that can be
  performed in just a few hours on a standard desktop computer.  The method also allows the crystal structures
  to be ranked according in terms of their thermodynamic stability under a chosen
  set of external conditions (see figure 2).

figure 2