<div dir="ltr">Dear All, I will be very thankful if anyone of the developers team reply. I want to be sure that this is not a serious issue in my simulations with EFIELD. Thank you with regards-- Pankaj On Wednesday, 2 July 2014 15:41:59 UTC+2, Pankaj Mishra wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Dear All, I am bit wondered about Berry Phase for periodic system during applying EFIELD. As i read in this paper (Quantum-Mechanical Position Operator in Extended Systems; DOI: 10.1103/PhysRevLett.89.157602), the position operator (defined within the Schrödinger representation in the standard way) becomes meaningless when periodic boundary conditions are adopted for the wave function. Then we require Berry Phase theory. In the old version of CP2K 2.1, there was a column for Berry Phase. But that has been removed in later versions. May i know that how this has been taken care in the newer version? Do you expect some discrepancy during application of efield on periodic system? I hope for some reply. Thank you in advance!!! with regards-- Pankaj Mishra </div></blockquote></div>