Crawford, TD; Yang, W, *The Hartley basis functions and transform: alternatives to plane waves and the Fourier transform*,
Chemical Physics Letters, vol. 192 no. 1
(1992),
pp. 45-48 .
**Abstract:**

*The Hartley "cas" basis functions are presented as alternatives to the well-known plane waves in electronic structure and molecular dynamics calculations. The cas functions are real, amenable to a fast transform, and thus offer the advantage of improved computational efficiency. The basis functions are tested in the calculation of the energy eigenvalues of a Morse oscillator, and are found to give results equal in accuracy to the plane waves. © 1992.*