Calculation of the A Band Shape in KC1:Au-in the D-Mode Model -BY S. MURAMATSU and N. SAKAMOTO Recently various perturbative optical m e a s u r e m e n t s such as s t r e s s and magnetically induced dichroisni in the A band (spin-orbit allowed So -3P1) of the Auc e n t r e in KC1 w e r e reported by Lemoyne et al. (LDBD) /l/. Analyzing the experimental r e s u l t s by the method of moments, they have shown that the excited triplet s t a t e s originating f r o m p s t a t e s are equally coupled t o both E and r 2 mod e s . The situation of equal coupling t o the two modes had been found in the F+ centre of C a O /2/. In the c a s e of KCl:Au-, the coupling with al mode predominates, but Ca0:F' is a c a s e where the al does not dominate. A s suggested by LDBD / l / , this difference is reflected in the broad-band shape of the absorption:The band shape of Ca0:F' is s q u a r e r than Gaussian shape /2/. while that of KC1:Au-is r a t h e r Gaussian-like