Dear Terry, The dipole results need post-processing. One needs to subtract n x polarization quantum to obtain a meaningful polarization. n is an integer.
Consider a simple dielectric like MgO at zero field. pw.x may give you different dipoles in all directions, although physically in all directions the net dipoles are zero. If you post-process as I indicated above you get zero dipole as it should. A good starter on this topic is this paper: https://www.sciencedirect.com/science/article/abs/pii/S0022459612003234 A free arXiv version of it is also available. Mostafa AUC
_______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
