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 Schrodinger 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 (0)=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. (c) 2016 Wiley Periodicals, Inc.