Above-threshold ionization spectrum of hydrogen using B-spline functions

We present a method for the accurate calculation of above-threshold ionization (ATI) spectra of single active electron systems. The technique involves the expansion of the radial wavefunction onto a set of B-spline functions. Results of ATI in hydrogen are presented and particular features of the spectra are discussed. A detailed study of the sensitivity of the results to the critical parameters is given to emphasize the importance of the necessity of a high degree of convergence in such calculations. Finally, we discuss and quantitatively justify the use of L(2) methods in investigations of ATI.