On Mar 28, 2012, at 15:25 , Wei Lai wrote: > I created a virtual tetragonal MgO cell with c/a ratio as 1.4. > I was expecting this ratio will become close to 1.4142 (cubic) > after relaxation.
your k-point grid is not symmetric and produces a small symmetry breaking. A denser grid yields a more symmetric final structure P. --- Paolo Giannozzi, Dept of Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
