JOURNAL OF CHEMICAL PHYSICS, vol. 116, no. 9, page. 3800 - 3804, 2002-03-01
PHYSICAL REVIEW B, vol. 63, no. 7, 2001-02-15
PHYSICAL REVIEW B, vol. 66, no. 11, 2002-09-15
PHYSICAL REVIEW B, vol. 64, no. 23, 2001-12-15