We investigate the electronic structure of the beryllium atom subjected to a strong magnetic field in the regime 0 ≤ γ ≤ 10 a.u. The ground as well as many excited states of spin singlet, triplet and quintet multiplicity covering the magnetic quantum numbers |M | = 0, 1, 3, 6 for both positive and negative z−parity are discussed and analyzed. Total and one-particle ionization energies are presented. Transition wavelengths as a function of the field strengths for allowed dipole transitions are provided.

The lowest bound states of the hydrogen negative ion and negative donor systems in a homogeneous magnetic field are investigated theoretically via a full configuration-interaction approach with an anisotropic Gaussian basis set. The broad magnetic field regime ␥ϭ8ϫ10 Ϫ4 Ϫ4ϫ10 3 is covered. Nonrelativistic total energies, electron detachment energies, and transition wavelengths are presented assuming an infinite nuclear mass. The binding mechanisms are discussed in detail. The accuracy for the energies is enhanced significantly compared to previously published data.

The electronic structure of the lithium atom in a strong magnetic field 0 <= gamma <= 10 is investigated. Our computational approach is a full configuration interaction method based on a set of anisotropic Gaussian orbitals that is nonlinearly optimized for each field strength. Accurate results for the total energies and one-electron ionization energies for the ground and several excited states for each of the symmetries ^20^+, ^2(-1)^+, ^4(-1)^+, ^4(-1)^-, ^2(-2)^+, ^4(-2)^+, $^4(-3)^{+}$ are presented. The behaviour of these energies as a function of the field strength is discussed and classified. Transition wave lengths for linear and circular polarized transitions are presented as well.Comment: 12 pages, 13 figures, accepted for publication in Phys. Rev.

We investigate the helium atom embedded in a superstrong magnetic field γ = 100-10000 au. All effects due to the finite nuclear mass for vanishing pseudomomentum are taken into account. The influence and the magnitude of the different finite mass effects are analyzed and discussed. Within our full configuration interaction approach calculations are performed for the magnetic quantum numbers M=0,−1,−2,−3, singlet and triplet states, as well as positive and negative z parities. Up to six excited states for each symmetry are studied. With increasing field strength the number of bound states decreases rapidly and we remain with a comparatively small number of bound states for γ = 10 4 au within the symmetries investigated here.

We investigate the electromagnetic transition probabilities for the helium atom embedded in a superstrong magnetic field taking into account the finite nuclear mass. We address the regime γ = 100 − 10 000 a.u. studying several excited states for each symmetry, i.e. for the magnetic quantum numbers 0, −1, −2, −3, positive and negative z parity and singlet and triplet symmetry. The oscillator strengths as a function of the magnetic field, and in particular the influence of the finite nuclear mass on the oscillator strengths are shown and analyzed.