1. Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Uppsala SE-751 20, Sweden
2. Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm SE-100 44, Sweden
3. AB Sandvik Materials Technology R&D Center, Sandviken SE-811 81, Sweden
4. Division of Engineering Materials, Department of Management and Engineering, Linköping University, Linköping SE-581 83, Sweden
5. Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Budapest H-1525, Hungary