Session D40 - Poster Session I.
POSTER session, Monday afternoon, March 12
Exhibit Hall, Washington State Convention Center
We have used a first-principles computational scheme to investigate the Raman spectra of the Ge_xS_(1-x-y)I_y family of glasses. The scheme involves forming cluster models of atomic arrangements expected to be important in the glasses. Density-functional theory calculations are carried out on these models to optimize the bond lengths and bond angles, and to compute the vibrational normal modes. To make contact with experiment, the Raman scattering strength of each mode is also calculated, using a new, first-principles method (see Jackson et al., Phys. Rev. B 60, R14 985 (1999)). The results show clear features related to I atoms replacing S atoms in GeX_4 tetrahedra. These features are in good agreement with recent measurements of Boolchand et al. (unpublished).