1. Department of Applied Mathematics, University of Crete, GR-71409, Heraklion, Crete, Greece
2. Institute of Applied and Computational Mathematics FORTH, GR-71110 Heraklion,
Crete, Greece
3. Department
of Materials Science
and Technology, University of Crete, Greece
4. Institute for Electronic Structure
and Laser, FORTH, Heraklion, Crete, Greece