Calculating change in electronic polarization due LCALCPOL
Hello,
We are trying to apply calculate the electric polarization induced by an applied magnetic field in a magnetoelectric material, analogously to what is done in this work. https://journals.aps.org/prl/abstract/1 ... 106.107202
However, we are a bit confused about how to do this using LCALCPOL. The documentation seems to imply that only a single calculation is needed, but since it is the change in polarization that is relevant, it seems that we would have to do two calculations, one with no magnetic field applied, and one with magnetic field applied (via BEXT), where for the latter we read in the converged CHGCAR from the converged calculation with no magnetic field self-consistently, and both calculations are done with LCALCPOL=.TRUE. But it is not at all clear if this is the correct procedure based on the wiki page.
Right now, as a first step we have trying a single calculation using LCALCPOL with a finite applied magnetic field, and all three components of the ionic and electronic polarization are exactly zero.
Thank you in advance!