Abstract
Uncertainties in potential curves determined by the Rydberg—Klein—Rees (RKR) method which result from approximations inherent in current applications of the method and from experimental errors are discussed. The use of the RKR method to extrapolate potential curves beyond the region known spectroscopically is discussed, with calculations on the X 1Σg+ state of H2 presented as examples. Application is made to the X 1Σ+ and a 3II states of GaH, InH, and TlH, with particular emphasis on the correlation of states from the lower MO configurations with the states of the separated atoms.