Hopefully this was obvious to you all, but on the last problem you use the Morse potential function (eq 13.146) and not eqn 13.82 as listed. -- Andrew J. Pounds, Ph.D. (pounds_aj at mercer.edu) Professor of Chemistry and Computer Science Mercer University, Macon, GA 31207 (478) 301-5627 http://faculty.mercer.edu/pounds_aj