Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 15: Poster: Interaction with strong or short laser pulses

A 15.3: Poster

Monday, March 17, 2014, 16:30–18:30, Spree-Palais

Orthohelium in laserfields beyond TDDFT: doubly-excited states made simple using TDRNOT — •Julius Rapp, Martins Brics, and Dieter Bauer — Institut für Physik, Universität Rostock

Time-dependent renormalized natural orbital theory (TDRNOT) is a novel many-particle method [1] to investigate correlated dynamics of quantum systems. We explore the capabilities of TDRNOT and benchmark its performance regarding the application to an exactly solvable one-dimensional helium model atom in both singlet and triplet configuration. Despite being in an early stage of development, TDRNOT outperforms “mature” techniques such as practicable time-dependent density functional theory (TDDFT) concerning the description of highly correlated phenomena such as doubly-excited states, autoionization, and Fano profiles. Moreover, the treatment of, e.g., Rabi oscillations is more intuitive than it is within TDDFT, considering the exotic features of the exact exchange-correlation (XC) functional there such as inital-state dependence, non-locality in time, and similar.

We discuss the result of a recent modification to the TDRNOT scheme [2] which substantially improves the description of the spin-triplet in particular. One remarkable feature compared to TDDFT is the presence of doubly-excited states in the linear response spectrum, whose energies approach the correct values if enough natural orbitals are included in the calculation. As an outlook, we also address dynamics induced by laser fields beyond linear response.

[1] M. Brics, D. Bauer, Phys. Rev. A 88, 052514 (2013).

[2] J. Rapp, M. Brics, D. Bauer (submitted).