Multi-channel dynamics in high harmonic generation of aligned CO₂: ab initio analysis with time-dependent B-spline algebraic diagrammatic construction

Abstract

Here we present a fully ab initio study of the high-order harmonic generation (HHG) spectrum of aligned CO molecules. The calculations have been performed by using the molecular time-dependent (TD) B-spline algebraic diagrammatic construction (ADC) method. We quantitatively study how the sub-cycle laser-driven multi-channel dynamics, as reflected in the position of the dynamical minimum in the HHG spectrum, is affected by the full inclusion of both correlation-driven and laser-driven dipole interchannel couplings. We calculate channel-resolved spectral intensities as well as the phase differences between contributions of the different ionization-recombination channels to the total HHG spectrum. Our results show that electron correlation effectively controls the relative contributions of the different channels to the total HHG spectrum, leading to the opening of the new ones (1Π, 1Σ), previously disregarded for the aligned molecular setup. We conclude that inclusion of many-electron effects into the theoretical interpretation of molecular HHG spectra is essential in order to correctly extract ultrafast electron dynamics using HHG spectroscopy.

A detailed investigation of single-photon laser enabled Auger decay in neon

“…We calculated the single-atom, phase-dependent, channel-resolved asymmetry using the time-dependent (TD) B-spline algebraic diagrammatic construction (ADC) ab initio method [14][15][16][17]. The single-particle basis set consists of spherical harmonics Y lm (θ, j) for the angular part and B-spline functions B i (r) for the radial coordinate.…”

“…respectively) is performed by means of the general complex Lanczos, or Arnoldi-Lanczos, algorithm[16,17,19]. The calculations have been performed using a parabolic-linear B-spline knot sequence[14,20] with a radial box radius of = R 1200 max a.u.…”

Attosecond-Resolved Electron Dynamics in Many-Electron Atoms: Quantitative Theory and Comparison with Measurements

“…Even when the initial-state electronic structure is favorable for their formal implementation (i.e., single-determinantal closed-shell ground states), methods such as those in [40][41][42][43][44][45] express the content of the SSEA only in an approximate way. However, as I already mentioned in Section 3.2, for the time being approximate treatments may indeed be necessary for the study of molecules.…”

Partial cross sections and interfering resonances in photoionization of molecular nitrogen

“…The former, being the techniques of quantum chemistry, generally rely on an expansion of the wave function in terms of Gaussian basis functions, while the latter frequently rely on the use of compact-support functions such as B-splines [6][7][8][9] or discrete variable representations in combination with finite elements methods (FE-DVR) [10,11]. More recently it has been shown that B-Splines can be used in combination with algebraic diagramatic construction (ADC) to obtain photoionization cross sections in atomic systems [12] and to study the effect of electron correlation in high harmonic generation [13]. Both, B-spline and FE-DVR based methods, have proven highly successful in their respective domains of application, due to the analytical simplicity of Gaussian functions and the flexibility of B-splines and FE-DVR at long range, but prove ill suited beyond it.…”