2-ELECTRON ATOMS IN SHORT INTENSE LASER-PULSES

We discuss a method of solving the time-dependent Schrodinger equation for atoms with two active electrons in a strong laser field, which we used in a previous paper [A. Scrinzi and B. Piraux, Phys. Rev. A 56, R13 (1997)] to calculate ionization, double excitation, and harmonic g eneration in helium by shea laser pulses. The method employs complex s caling and an expansion in an explicitly correlated basis. Convergence of the calculations is documented and error estimates are provided. T he results for He at peak intensities up to 10(15) W/cm(2) and wavelen gth 248 nm are accurate to at least 10%. Similarly accurate calculatio ns are presented for electron detachment and double excitation of the negative hydrogen ion. [S1050-2947(98)00208-X].