A. Cordoba et al., A TRIGONOMETRIC SUM RELEVANT TO THE NONRELATIVISTIC THEORY OF ATOMS, Proceedings of the National Academy of Sciences of the United Statesof America, 91(13), 1994, pp. 5776-5778
We extend Van der Corput's method for exponential sums to study an osc
illatory term appearing in the quantum theory of large atoms. We obtai
n an interpretation in terms of classical dynamics and we produce shar
p asymptotic upper and lower bounds for the oscillations.