next up previous contents
Next: Frequency dependent GW calculations Up: Optical properties and density Previous: LRPA: local field effects   Contents


Vibrational frequencies, relaxed-ion static dielectric tensor and relaxed-ion piezoelectric tensor

Setting IBRION=8 or IBRION=7 selects the calculation of the interatomic force constants using density functional perturbation theory. For IBRION=8, symmetry is taken into account, whereas IBRION=7 neglects symmetry considerations and is thus usually significantly more expensive. If IBRION=7 (or IBRION=8) and LEPSILON=.TRUE. is selected, the relaxed-ion static dielectric tensor, or low frequency dielectric tensor, and the relaxed-ion piezoelectric tensors are determined [84]. All values are collected and printed at the end of the OUTCAR file (see also Sec. 6.21.7). Specifically the ionic contribution to the piezoelectric tensor is printed after


 PIEZOELECTRIC TENSOR IONIC CONTR  for field in x, y, z        (C/m^2)
and the ionic contributions to the dielectric tensor are printed after:

 MACROSCOPIC STATIC DIELECTRIC TENSOR IONIC CONTRIBUTION
Note that LRPA=.FALSE. must be selected to obtain these values.



Georg Kresse
2009-04-23