REDUCTION FACTORS, TUNNELING SPLITTING AND ZERO-PHONON LINE INTENSITY IN TXPI-2 AND T X(PI-2+EPSILON) JAHN-TELLER SYSTEMS

First- and second-order reduction factors for the Jahn-Teller systems T (X)( tau 2(X) in ) and T (X) tau 2 are calculated using a numerical perturbation method, and checked analytically at strong and weak coupling. Those for T (X) tau 2 are compared with ones produced analytically by Bates and Dunn (1989), and the general agreement is good. An attempt to find an asymptotic formula for the tunnelling splitting showed its form to be still uncertain with the splitting as small as 10-7 pi omega , but the fit with a WKB calculation is good. The zero-phonon line intensity in T (X) tau is calculated numerically and analytically.