Ab initiostudy of high-lying doubly excited states of helium in static electric fields: Complex-scaling generalized pseudospectral method in hyperspherical coordinates

Abstract

We present a complex-scaling (CS) generalized pseudospectral (GPS) method in hyperspherical coordinates (HSC) for ab initio and accurate treatment of the resonance energies and autoionization widths of two-electron atomic systems in the presence of a strong dc electric field. The GPS method allows nonuniform and optimal spatial discretization of the two-electron Hamiltonian in HSC with the use of only a modest number of grid points. The procedure is applied for the first precision calculation of the energies and autoionization widths for the high-lying 1 S e , 1 P o , 1 D e , and 1 F o (n = 10-20) doubly excited resonance states of He atoms. In addition, we present a theoretical prediction of the energies and widths of high-lying doubly excited resonance states of 1 P o (n = 8-15) in external dc electric field strengths of 3.915-10.44 kV/cm. The calculated dc-field perturbed high-lying resonance energies are in good agreement with the latest experimental data.

Investigation of the Spatio-Temporal Characteristics of High-Order Harmonic Generation Using a Bohmian Trajectory Scheme

“…More crucially, this theory considers ionized electrons to be free electrons traveling in a laser field, ignoring the influence of coulomb potential. The phase of harmonic emission is also affected by the change in coulomb potential, which in turn influences the intensity and interference structure of harmonics [35][36][37][38]. HHG obtained in the experiment is a coherent superposition of all atomic harmonics in the gas target so that the precision of the harmonic phase of a single atom will affect the accuracy of the harmonic calculation as a whole [39].…”

Multielectron effects in the photoelectron momentum distribution of noble-gas atoms driven by visible-to-infrared-frequency laser pulses: A time-dependent density-functional-theory approach

“…The KS effective potential of the atom is calculated by using the local density approximation with a self-interaction correction (LDA-SIC) [21]. This scheme has been successfully used in the past to calculate high harmonic spectra of He, Ne and Ar [22] atoms, the strong-field ionization of Li and beryllium atoms [23], the resonance energies of He Rydberg states [24], the Cooper minimum in the high harmonic spectra of an Ar atom [25,26], and the transient absorption spectra of a He atom [27]. This paper complements these works with the PMD calculation of He, Ne and Ar atoms.…”