Physics and Chemistry of Minerals

, Volume 35, Issue 7, pp 359–366

The compressibility and high pressure structure of diopside from first principles simulation


    • Department of Earth SciencesUniversity of Cambridge
  • Richard P. Tyer
    • STFC Daresbury Laboratory
  • Richard P. Bruin
    • Department of Earth SciencesUniversity of Cambridge
  • Martin T. Dove
    • Department of Earth SciencesUniversity of Cambridge
Original Paper

DOI: 10.1007/s00269-008-0229-3

Cite this article as:
Walker, A.M., Tyer, R.P., Bruin, R.P. et al. Phys Chem Minerals (2008) 35: 359. doi:10.1007/s00269-008-0229-3


The structure of diopside (CaMgSi2O6) has been calculated at pressures between 0 and 25 GPa using the planewaves and pseudopotentials approach to density functional theory. After applying a pressure correction of 4.66 GPa to allow for the under-binding usually associated with the generalized gradient approximation, cell parameters are in good agreement with experiment. Fitting to the third-order Birch–Murnaghan equation of state yields values of 122 GPa and 4.7 for the bulk modulus and its pressure derivative. In addition to cell parameters, our calculations provide all atomic positional parameters to pressures considerably beyond those currently available from experiment. We have analyzed these data in terms of polyhedral rigidity and regularity and find that the most compressible Ca polyhedron becomes markedly less anisotropic above 10 GPa.


DiopsideDensity functional theoryEquation of statePyroxeneCompression

Supplementary material

269_2008_229_MOESM1_ESM.pdf (596 kb)
Supplementary material (PDF 595 kb)

Copyright information

© Springer-Verlag 2008