Gaussian continuum basis functions for calculating high-harmonic generation spectra

The computation of high‐harmonic generation spectra by means of Gaussian basis sets in approaches propagating the time‐dependent Schrödinger equation was explored. The efficiency of Gaussian functions specifically designed for the description of the continuum proposed by Kaufmann et al. (J Phys B 1989, 22, 2223) was investigated. The range of applicability of this approach was assessed by studying the hydrogen atom, that is, the simplest atom for which “exact” calculations on a grid could be performed. The effect of increasing the basis set cardinal number, the number of diffuse basis functions, and the number of Gaussian pseudo‐continuum basis functions for various laser parameters was notably studied. The results showed that the latter significantly improved the description of the low‐lying continuum states, and provided a satisfactory agreement with grid calculations for laser wavelengths λ0 = 800 and 1064 nm. The Kaufmann continuum functions, therefore, appeared as a promising way of constructing Gaussian basis sets for studying molecular electron dynamics in strong laser fields using time‐dependent quantum‐chemistry approaches. © 2016 Wiley Periodicals, Inc.