Posts Tagged ‘time-dependent’

stsm-SU-UAMSTSM by  Eva Lindroth and Tor Kjellsson, Stockholm University with Luca Argenti and Fernando Martín, Universidad Autonoma de Madrid
On November 15th, 2013 (7 days)


Time-dependent atomic photoionisation with a Multi-Configuration-Hartree-Fock close-coupling approach

This STSM concerned the collaboration between the COST nodes in Stockholm and Madrid to build a new program to solve the timedependent Schrodinger equation (TDSE) for  arbitrary poly-electronic atoms under the action of pulsed fields.

The program under  construction extends a Multi-Con guration-Hartree-Fock (MCHF) atomic-structure package to include the coupling to an ionized electron. It is based on close-coupling ionization states built from MCHF parent-ion states coupled to radial B-splines. Prior to the STSM, the package could already reproduce photoionization cross sections for arbitrary atoms with both the initial bound state and the final continuum states described
at the MCHF level as detailed in a recent publication [Carette, Dahlstrom, Argenti
and Lindroth 2013 Phys. Rev. A 87 023420].

As a result of the STSM:

  • The inclusion of the K-matrix package for the calculation of multichannelsingle-ionisation scattering states to resolve energetically and angularly the partial photoelectron spectra encoded in the electronic wave packetsobtained from simulations of pump-probe experiments on atoms was started. A similar integration technique was already successfully demonstrated in 2010 [Argenti et al. 2013, Phys. Rev. A 87 053405].
  • The user friendly setup of the package was tested
  • The benchmarking of neon- and argon photoionization, and especially the issue of how to obtain a correct energy position of the so-called Cooper minima in argon was discussed.

STSM by  Francisca Mota-Furtado,Royal Holloway, University of London with Bernard Piraux, Universitè Catholique de Louvain, Louvain-la-Neuve
On August 22th, 2013 (9 days)

Time-dependent methods for strong laser fields

Robust time propagators are required to solve the Time Dependent Schrödinger Equation (TDSE) for atomic, molecular and solid state systems as for example when matter interacts with an intense low frequency laser field.

The direct numerical ab initio solution of the TDSE using spectral methods leads to large systems of first order equations with a high degree of stiffness. We focussed on two explicit methods, Fatunla’s method and the Arnoldi algorithm.  Both of these methods have optimum stability properties but they differ in the degree of accuracy they are able to reproduce. We identified strategies to use them both successfully.

During the short visit we finished a joint paper with our hosts on this topic which has been submitted to Physical Review A.