Eur. Phys. J. D (2016) 70: 190
https://doi.org/10.1140/epjd/e2016-70152-3

Regular Article

Calculation of resonance states of positronic lithium atom^*

Department of Chemistry, Tohoku University, 980-8578 Sendai, Japan

^a e-mail: t.ymst@dc.tohoku.ac.jp

Received: 29 February 2016
Received in final form: 19 July 2016
Published online: 15 September 2016

Abstract

Feshbach resonance states of positronic lithium atom are precisely calculated with a Gaussian expansion method. By adopting a Lorentzian formula for density of state, resonance energies and widths are systematically determined from series of energy levels calculated by a real scaling method. We identify Feshbach resonance states between Li (2p) + e⁺ and Li (4s) + e⁺ thresholds and the results are in good agreement with previous works with the real scaling method and complex scaling method. Our results of a dipole series of resonances supported by ion-dipole interaction of Li⁺-Ps (n = 2), whose existence has been pointed out by previous works, show a good agreement with the latest calculation with a complex scaling calculation. We point out that an accuracy of the model potential for the electron and positron from the atomic ion is significant for the positronic atom formation process.