1. Division of Material Science
(Physics), Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
2. Division of Bioscience, Graduate
School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
3. Institut für Theoretische
Physik, Johannes Kepler Universität Linz, Altenberger Str. 69, 4040 Linz, Austria