Molecular crystal structure affects the bioavailability ofpharmaceuticals, the charge carrier efficiency of organicsemiconductors, the products of solid-state reactions, and the explosiveperformance of energetic materials.  Because different packingarrangements, or polymorphs, are often very close in energy, predictingmolecular crystal properties from first principles is extremelydifficult.  We have developed a new, fragment-based quantum/classicalhybrid model that makes it possible to apply high-level electronicstructure methods to molecular crystal structure prediction. This modeltreats intramolecular effects and short-range pairwise intermolecularinteractions quantum mechanically, while longer-range and many-bodyinteractions are approximated classically.  We will demonstrate thatthis model makes it possible to predict small-molecule crystal latticeenergies essentially to within experimental accuracy.  Then we willexamine its performance in more interesting polymorphic crystals, suchas aspirin and oxalyl dihydrazide.

Practical prediction of molecular crystal structures and properties from first principles

244th National Meeting (2012)

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