On the nonexistence of strictly diabatic molecular electronic bases

In a recent publication (M. Baer, A. Alijah, Chem. Phys. Lett. 319 (2000) 489), it is proposed that, contrary to a number of statements in the literature, it may indeed be possible to construct strictly diabatic electronic basis sets in molecular systems. We show that the result of Baer and Alijah is invalid.