Excitation of helium Rydberg states and doubly excited resonances in strong extreme ultraviolet fields: Full-dimensional quantum dynamics using exponentially tempered Gaussian basis sets

• Published in: The Journal of chemical physics Vol. 139; no. 10; p. 104314
• Main Authors: Kaprálová-Žďánská, Petra Ruth, Šmydke, Jan, Civiš, Svatopluk
• Format: Journal Article
• Language: English
• Published: United States 14.09.2013
• Subjects: ABSORPTION; ATOMIC AND MOLECULAR PHYSICS; CROSS SECTIONS; DENSITY; ELECTRIC DISCHARGES; EMISSION; EXTREME ULTRAVIOLET RADIATION; GAUSS FUNCTION; HELIUM; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MULTI-PHOTON PROCESSES; OSCILLATOR STRENGTHS; ROTATIONAL STATES; RYDBERG STATES; SIMULATION; WAVELENGTHS
• ISSN: 0021-9606; 1089-7690; 1089-7690
• DOI: 10.1063/1.4819495

Recently optimized exponentially tempered Gaussian basis sets [P. R. Kapralova-Zdanska and J. Smydke, J. Chem. Phys. 138, 024105 (2013)]10.1063/1.4772468 are employed in quantitative simulations of helium absorption cross-sections and two-photon excitation yields of doubly excited resonances. Linearly polarized half-infinite and Gaussian laser pulses at wavelengths 38–58 nm and large intensities up to 100 TW/cm2 are considered. The emphasis is laid on convergence of the results with respect to the quality of the Gaussian basis sets (typically limited by a number of partial waves, density, and spatial extent of the basis functions) as well as to the quality of the basis set of field-free states (typically limited by the maximum rotational quantum number and maximum excitation of the lower electron). Particular attention is paid to stability of the results with respect to varying complex scaling parameter. Moreover, the study of the dynamics is preceded by a thorough check of helium energies and oscillator strengths as they are obtained with the exponentially tempered Gaussian basis sets, being also compared with yet unpublished emission wavelengths measured in electric discharge experiments.