Computer simulations of organic solids and their liquid-state precursors

Representative calculations on 2-pyridone in its crystalline, liquid and solvated form, show the capabilities and the shortcomings of computer simulation techniques for the description of organic molecular systems. Both 'static' and 'dynamic' computations, meaning without and with the explicit treatment of thermal motion, are employed. Relationships of liquid and solution systems to the structure and thermodynamics of the crystalline solids are investigated as far as possible, with regards to efficient and systematic crystal structure prediction from molecular structure. The thesis to be discussed here is that a reliable theory for the prediction of the solid-state structure of small organic molecules must depend on an accurate thermodynamic and kinetic evaluation of the pathways for evolution from disorder to order, including liquid structuring and nucleation. Dynamic methods, including thermal motion, are indispensable for the accomplishment of this task, which remains today a faraway goal in structural physical chemistry.