EXTENDED ELECTRONIC STATES IN A FIBONACCI CHAIN

The electronic structure of a one-dimensional binary alloy A1 tau /B1 tau /2 (with tau being the golden mean) with atoms A and B distributed in a Fibonacci sequence is studied using a tight-binding model, in which variation in both the diagonal and the off-diagonal terms is treated simultaneously. In contrast to the previous diagonal and off-diagonal models, for the 'mixed' model the author finds an extended state. Also in the limiting case of the 'off-diagonal' model the state corresponding to E=0 is an extended state. These extended states are found to be independent of the arrangement of BA and BAA sequences in the Fibonacci chain.