Can someone tell me where possible cause of the problem ? I am using home made code where LCAO (using LDA and GGA) implemented for calculation of electronic structure. Calculating structure for Cr (BCC) gives 1 Ang off the potential minimum (3.6 A should be 2.88 A). I checked k point mesh, primitive vectors, core charge (18), and atomic positions. If I calculate for SC I am getting the right potential minimum at 2.88. Thank you so much for your help in advance.