Ground states of H, He, ..., Ne, and their singly positive ions in strong magnetic fields: The high-field regime - art. no. 022505

The electronic structure of the ground state and some excited states of neu tral atoms with the nuclear charge numbers 1 less than or equal to Z less t han or equal to 10 and their singly positive ions are investigated by means of our two-dimensional mesh Hartree-Fock method for strong magnetic fields 0.5 less than or equal to gamma less than or equal to 10 000. For gamma = 10 000 the ground-state configurations of all the atoms and ions considered are given by fully spin-polarized configurations of single-electron orbita ls with magnetic quantum numbers ranging from m = 0 to rn = -N + 1, where N is the number of the electrons. Focusing on the fully spin-polarized situa tion, we provide critical values of the magnetic-field strength for which c rossovers with respect to the spatial symmetries of the ground state take p lace. It is found that the neutral atoms and singly charged positive ions w ith 2 less than or equal to Z less than or equal to 5 have one fully spin-p olarized groundstate configuration, whereas for 6 less than or equal to Z l ess than or equal to 10 one intermediate fully spin-polarized configuration with an orbital of 2p(0) type occurs.