Correlation function quantum Monte Carlo calculations for ground and excited states of many-electron atoms and ions in neutron-star magnetic fields

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The goal of this project is to apply the correlation function quantum Monte Carlo (CF) method to the calculation of atomic data of medium-heavy atoms and ions in neutron star magnetic fields. The method, which allows for the calculation of both ground and excited states, and transition rates, has been successfully applied by Jones, Ortiz and Ceperley to the calculation of atomic data in weak neutron star magnetic fields. They used Hartree-Fock basis sets with spherical symmetry, which limited the maximum field strength they could study. These authors already remarked that a different basis set could be chosen for strong magnetic fields using the adiabatic approximation . This is exactly what we want to do: Take basis sets which account for the growing dominance of the cylindrical symmetry as the magnetic field is increased and to incorporate them into the CF algorithm. These basis states will be computed by a method that has been developed by us in a previously DFG funded project, namely, Hartree-Fock-Roothaan basis states, with admixtures from higher Landau levels, which even go beyond the adiabatic approximation. The importance of the project is twofold: On the methodological side we will test and demonstrate the scope and power of the CF method. On the physical side we will generate atomic data for wavelengths and oscillator strengths with unprecedented accuracy for medium-heavy atoms and ions in neutron star magnetic fields that are of immediate relevance to the analysis of features recently discovered in the thermal emission spectra of isolated neutron stars.