Natural orbitals of helium in linearly polarized laser fields★
Institut für Physik, Universität Rostock,
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Received in final form: 8 May 2018
Published online: 4 July 2018
Practicable equations of motion for the natural orbitals of a spin-singlet helium atom in a linearly polarized laser field are presented. The cylindrical symmetry of the two-electron problem with quantum number M = 0 is shown to yield a sparse expansion of natural orbitals in spherical harmonics. This optimization facilitates the propagation of renormalized natural orbitals of the helium atom. As a demonstration, the equations of motion are solved for a high-harmonic-generation process. In addition to the expected plateau from the single-active-electron picture, the spectrum of emitted radiation features a second plateau at higher harmonic orders.
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2018