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Prediction of the Mechanical Behaviour of Crystalline Solids



To explore the use of crystal inter-planar d-spacings and slip-plane interaction energies for predicting and characterising mechanical properties of crystalline solids.


Potential relationships were evaluated between mechanical properties and inter-planar d-spacing, inter-planar interaction energy, and dispersive surface energy as determined using inverse gas chromatography (IGC) for a set of pharmaceutical materials. Inter-planar interaction energies were determined by molecular modelling.


General trends were observed between mechanical properties and the largest inter-planar d-spacing, inter-planar interaction energies, and IGC dispersive surface energy. A number of materials showed significant deviations from general trends. Weak correlations and outliers were rationalised.


Results suggest that the highest d-spacing of a material could serve as a first-order indicator for ranking mechanical behaviour of pharmaceutical powders, but with some reservation. Inter-planar interaction energy normalised for surface area shows only a weak link with mechanical properties and does not appear to capture essential physics of deformation. A novel framework linking mechanical properties of crystals to the distinct quantities, slip-plane energy barrier and inter-planar interaction (detachment) energy is proposed.

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Correspondence to Jamshed Anwar.

Electronic supplementary material

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Supplementary Material S1

Experimental and optimised unit cell parameters for the materials examined using the CVFF (force field assigned charges) force field. Percentage deviations are shown in brackets. Deviations greater than 5% are shown in bold. (DOC 45 kb)

Supplementary Material S2

Experimental and optimised unit cell parameters for the materials examined using the Dreiding (Qeq charges) force field. Percentage deviations are shown in brackets. Deviations greater than 5% are shown in bold. (DOC 45 kb)

Supplementary Material S3

Experimental and optimised unit cell parameters for the materials examined using the Dreiding (Gasteiger charges) force field. Percentage deviations are shown in brackets. Deviations greater than 5% are shown in bold. (DOC 44 kb)

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Shariare, M.H., Leusen, F.J.J., de Matas, M. et al. Prediction of the Mechanical Behaviour of Crystalline Solids. Pharm Res 29, 319–331 (2012).

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  • mechanical properties
  • particle deformation
  • slip plane
  • molecular modelling
  • inter-planar interaction energy