1. Department of Physics and Astronomy, Amherst College, Amherst, MA 01002–5000, USA.
2. QCD Labs, Academy of Finland Centre of Excellence in Computational Nanoscience, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland.
3. University of Jyväskylä, Department of Mathematical Information Technology, P.O. Box 35, FI-40014 Jyväskylä, Finland.