1. Condensed Matter Theory Group, Department
of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
2. Pakistan Atomic Energy Commission (PAEC), P. O. Box. 2151, Islamabad, Pakistan
3. Department of Engineering Sciences, The Ångström
Laboratory, Uppsala University, Box 534,
SE-751 21 Uppsala, Sweden
4. Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm,
Sweden
5. Department of Physics, Central University of Rajasthan, NH-8, Bandarsindri,
Rajasthan 305801, India