[Pw_forum] Negative Polarization !!!

[Mojtaba Mirseraji]

Dear Mostafa

Thanks a lot



On 5/12/15, Mostafa Youssef <myoussef at mit.edu> wrote:
> Hi Mojtaba,
>
> Polarization is a vector, so negative or positive just indicate its
> direction. So no worries about negative polarization. But in periodic
> boundary conditions you may still need to add (subtract) multiples of the
> polarization quantum in order to get the "reasonable" value of the
> spontaneous polarization of the material.
>
> A favorite of mine which go over some of these difficulties is this  paper:
>
> http://journals.aps.org/prb/abstract/10.1103/PhysRevB.71.014113
>
>
> Mostafa Youssef
> MIT
>
>
>