Application of the many-electron weak-field asymptotic theory of tunneling ionization to atoms

The many-electron weak-field asymptotic theory (ME-WFAT) of tunneling ionization [Tolstikhin et al., Phys. Rev. A 89, 013421 (2014)] is applied to atoms. The procedure to extract the asymptotic coefficient of a Dyson orbital needed to implement the ME-WFAT from many-electron wave functions given by a linear combination of Slater determinants composed of one-electron orbitals, as is typically the case in practical atomic structure calculations, is discussed. It is shown that in the one-configuration approximation such wave functions enable one to consistently implement the theory and calculate the ionization rate. The effect of relaxation of the ionic orbitals and the dependence of the rate on the total orbital momentum and spin states of the atom and ion are considered. However, wave functions constructed by mixing several electronic configurations, maybe more accurate in some sense, do not have the correct asymptotic behavior required for implementing the ME-WFAT. The theory is illustrated by calculations for atoms of the first three periods with the use of one-electron orbitals obtained by the Hartree-Fock method.

Figure 1

Radial parts of the HF orbitals (7) for Be. Note a change of scale in both axes at $r=4$.

Figure 2

Same as in Fig. 1, but for Ar.

Figure 3

Function (11) for the ionizing orbitals in Be and Ar. Solid circles denote numerical data obtained using the HF program [15]. Dashed lines denote fits by polynomials of third order in $1/r$.

Figure 4

Function (11) for the ionizing orbital in $\mathrm{C}{(}^{2S+1}L)$. Solid circles denote numerical data obtained using the HF program [15]. Dashed lines denote fits by polynomials of third order in $1/r$.

Figure 5

Function (26) for $\mathrm{He}\left(1s2s{}^{3}S\right)$ calculated with one (solid line) and two (dashed line) configurations. The dotted window indicates the interval of $1/r$ used in the fitting.