1. Solid State Physics/The Nanometer
Structure Consortium, Lund University,
Box 118, SE-221 00 Lund, Sweden
2. Dept. of Mathematics, Physics
and Electrical Engineering, Halmstad University, Box 823, SE-301 18, Halmstad, Sweden
3. Institute for Solid State Physics, Jena University, Max-Wien-Platz 1, 07743 Jena, Germany
4. Division of Physics, School
of Computer Science, Physics and Mathematics, Linneaus University, 39233 Kalmar, Sweden