Crystal structure prediction intermolecular potential

Development of transferable intermolecular potentials for crystal structure prediction by empirical fitting... 

Thus, although this review is primarily about the intermolecular forces in organic crystal structures, the problems of balancing inter- and intramolecular forces is clearly a major aspect of the challenge that crystal structure prediction poses computational chemistry. It is also important to appreciate that tests of intermolecular potentials for crystal structure prediction and reproduction will be significantly more successful when the experimental molecular structure is used than when genuine predictions are made. 

Crystal structure prediction The field of organic crystal structure prediction remains one of the best testing grounds for intermolecular potentials. Acciuades need not be as high as that needed for spectroscopic calculations, but the effects of molecular flexibility and many-body non-additivity need to be accounted for. See Price (2008, 2009) for recent reviews of this subject. For a description of dispersion-corrected DFT methods specially parametrized for organic crystals see Neumann and Perrin (2005). For a comprehensive examination of the role of detailed distributed multipole models in this field see Day et al. (2005). 

Mooij, W. T. M. van Duijneveldt, F. B. van Duijneveldt-van de Rijdt, J. G. C. M. van Eijck, B. P. Transferable ab initio intermolecular potentials. 1. Derivation from methanol dimer and trimer calculations, J. Phys. Chem. A1999,103, 9872-9882 Moij, W. T. M. van Eijck, B. P Kroon, J. Transferable ab initio intermolecular potentials. 2. Validation and application to crystal structure prediction, J. Phys. Chem. A 1999,103, 9883-9890. 

For parameters taken from crystal structures, no systematic predictions can be made of how the intermolecular interactions in the crystal may affect distances and angles. These potential solid state effects preclude comparisons within a level of several hundredths of an A for bond lengths and several degrees for angles. Operational effects are particularly large for C-H bonds, which are characteristically smaller in crystallographic studies compared to those found by the other methods. 

Early models Intermolecular potentials suitable for MD or MC simulations were developed for C mim + and [C2mim]+ ions [11], The predicted crystal structures... 

The type of model potential that is sufficient to predict a molecular crystal structure is very dependent on the shape of the molecule. If the shape has many well-defined protrusions and cavities, so that there is only one way that it can pack densely with a tight fitting of the protrusions of one molecule into the cavities of its neighbours, then any potential which represents this shape and has an attractive component will be acceptable. However, many shapes, such as discs or cylinders, can close pack in many ways, each generating a range of structures with differing tilt angles, etc. In these cases, the chemical nature of the atoms and resultant intermolecular forces determine which of the reasonably close-packed structures is adopted. 

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