1. Faculty of Physics and Center for Computational Materials Science, University of Vienna, Kolingasse 14-16, A-1090 Vienna, Austria
2. Vienna Doctoral School in Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
3. School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
4. School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
5. VASP Software GmbH, Sensengasse 8/12, A-1090 Vienna, Austria