Category:Berry phases

The polarization in a periodic system can be computed using the berry phase formulation of the polarization (often referred to as the modern theory of polarization). The calculation of the polarization is activated using LBERRY. To compute the three components of the polarization vector, we recommend using LCALCPOL.

With a method to compute the polarization, we can compute the ground state with a finite electric field applied to the system.

Finally, by applying a small electric field EFIELD_PEAD along the three cartesian directions and computing the polarization, forces, and stress tensor it is possible to obtain the dielectric tensor, the born-effective charges, and the piezoelectric tensor. These calculations can be automated inside VASP using LCALCEPS.