Quantum Monte Carlo studies of the ground states of heavy atoms in neutron-star magnetic fields

The 'released-phase' diffusion quantum Monte Carlo method is used to calculate the ground-state energies of atoms with nuclear charges from Z=2,3,4,...,26 for magnetic field strengths relevant for neutron stars. The feature of our study is the use of adiabatic approximation wave functions as guiding wave functions to initialize the quantum Monte Carlo procedure. Our calculations are motivated by the discovery of broad features in the thermal spectra of isolated neutron stars, which may be due to heavy atoms. Our results confirm previous results for nuclear charge numbers up to 10, and are the most accurate ones available in the literature to date for Z>10.