Convergence

Cutoff Energy

All calculations were performed with the experimental unit cell, with full optimisation of the atomic positions within the symmetry constraints of the space-group.  The PBE functional was used with a 7,6,5 Monkhurst-Pack grid.  In the tables below \(\epsilon_{ionic}\) and \(\epsilon_{elec}\) are the ionic and electronic contributions respectively to the permittivity at zero frequency.  Calculations of the ionic and electronic contributions to the permittivity and the frequencies were performed with the Density Functional Perturbation Theory (DFPT) module of the packages considered.  No sum rules were used in the calculation of the phonon frequencies as calculated by the DFT packages.  However, the values reported in the tables and the mean squared shifts in frequency were calculated using the PDielec package, with the translational phonon modes projected out.
In the tables the mean squared frequency shifts are calculated for all the optical phonon modes at the gamma point.  The mean squared frequency shifts given in brackets are calculated ignoring the lowest non-zero phonon frequency.

Vasp