Exact two-electron wave packet dynamics of H_2 in an intense alser field: Formation of localized ionic states H~+H~-

摘要

We have deverloped an efficient grid method that can accurately deal with the electronic wave packet dynamics of two-electron systems in three-dimensional (3D)space. By using the dual transformation technique, we remove the numerical difficulties arising form the singularity of the attractive Coulomb potential. Electron-electron repulsion is incorporated into the wave packet propagation scheme without introducing any approximations. The exact electronic dynamics of H_2 is simulated for the first time. At small internuclear distances(e.g.,R = 4 a.u), an ionic component characterized by the structure H~+H~- is created in an intense laser field #ipsilon#(t) (intensity > 10~(13) W/cm~2 and #gamma# approx = 720nm) because an electron is transferred from the nucleus around which the dipole interaction energy for the electron becomes higher with increasing |#epsilon#(t)|. The localized ionic structure is identifield with the H~- anion at the nucleaus around which the dipole interaction neergy becomes lower. Tunneling ionization proceeds via the formation of such a localized ionic structure, and direct ionization from the the covalent structure is much smaller; the localized ionic structure polays the dominant doorway s tate to ionization of H~2