In the strong field molecular tunneling ionization theory of Tong et al. [Phys. Rev. A 66, 033402 (2002)], the ionization rate depends on the asymptotic wavefunction of the molecular orbital from which the electron is removed. The orbital wavefunctions obtained from standard quantum chemistry packages in general are not good enough in the asymptotic region. Here we construct a one-electron model potential for several linear molecules using density functional theory (DFT). We show that the asymptotic wavefunction can be improved with an iteration method and after one iteration accurate asymptotic wavefunctions and structure parameters are determined. With the new parameters we examine the alignment-dependent tunneling ionization probabilities for several molecules and compare with other calculations and with recent measurements, including ionization from inner molecular orbitals.

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We analyzed the discrepancy of the angular dependence of strong-field ionization for CO 2 among the different theoretical calculations and experiments. Using a more accurate ground-state wave function of CO 2 in the asymptotic region, we showed that the accuracy in the earlier tunneling ionization theory of Tong et al. ͓Phys. Rev. A 66, 033402 ͑2002͔͒ is much improved. We also concluded that the angular dependence deduced from the experiment of Pavičić et al. ͓Phys. Rev. Lett. 98, 243001 ͑2007͔͒ appears to be too narrowly distributed.