Bug in the cell-optimization

xujroman leit... at matcalc.de
Mon Sep 7 09:46:32 UTC 2009

Dear CP2K users,

I am performing a cell optimization using Cell_Opt and Geo_Opt for
bulk Si.
However, I recognized a bug during the setup of the unit cell.

If the starting cell vectors are given along arbitrary directions,
CP2K performes a coodinate transformation so that the first cell
vector (A) points along the x-axis. However, the atomar basis in the
unit cell is not transformed. That leads to a completely different
(wrong) atomic structure taking the periodic boundary conditions into

The most simple way to avoid this bug, is to use cell vectors in such
a way that the A vector is parallel to the x-axis.

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