دانلود رایگان مقاله طیف فوتوالکترون با Qprop و t-SURF

Abstract

Calculating strong-field, momentum-resolved photoelectron spectra (PES) from numerical solutions of the time-dependent Schrödinger equation (TDSE) is a very demanding task due to the large spatial excursions and drifts of electrons in intense laser fields. The time-dependent surface flux (t-SURFF) method for the calculation of PES [Tao and Scrinzi (2012)] allows to keep the numerical grid much smaller than the space over which the wavefunction would be spread at the end of the laser pulse. We present an implementation of the t-SURFF method in the well established TDSE-solver Qprop [Bauer and Koval (2006)]. Qprop efficiently propagates wavefunctions for single-active electron systems with spherically symmetric binding potentials in classical, linearly (along z) or elliptically (in the xy-plane) polarized laser fields in dipole approximation. Its combination with t-SURFF makes the simulation of PES feasible in cases where it is just too expensive to keep the entire wavefunction on the numerical grid, e.g., in the long-wavelength or long-pulse regime

5. Summary

We incorporated the time-dependent surface flux method (t-SURFF) for the calculation of momentum-resolved photoelectron spectra (PES) into the Qprop package. In that way we facilitate the simulation of momentum-resolved PES up to the fastest relevant electron energies (typically ten times the ponderomotive energy) for laser parameters that were inaccessible with the previous version of Qprop based on the window-operator method. In fact, while t-SURFF gets along with grid sizes of the order of the quiver amplitude, the window operator method requires the full, very delocalized wavefunction at the end of the pulse. Especially for longwavelengths, high intensities, and many laser cycles t-SURFF is numerically much more efficient than the window operator approach as far as the energetic electrons are concerned. Complementary, the slow electrons (and the bound part of the spectrum) can still be calculated using the window operator since the necessary information is contained in the (non-absorbed) wavefunction on the small grid within the t-SURFF boundary. Several examples were provided, whose execution should enable users to adapt Qprop to their own problems.