The boron atom and boron positive ion in strong magneticfields

Abstract

The ground and a few excited states of the boron atom inexternal uniform magnetic fields are calculated by means of a 2Dmesh Hartree-Fock method for field strengths ranging from zeroup to 2.35×109 T. With increasing field strength theground state of the B atom undergoes five crossovers involvingsix different electronic configurations which belong to threegroups with different spin projections Sz = -1/2,-3/2,-5/2. Forweak fields the ground state configuration arises from thefield-free 1s22s22p-1, Sz = -1/2 configuration.With increasing field strength the ground state involves thefour Sz = -3/2 configurations 1s22s2p02p-1, 1s22s2p-13d-2,1s22p02p-13d-2 and 1s22p-13d-24f-3, followed by the fullyspin-polarized Sz = -5/2 configuration 1s2p-13d-24f-35g-4.The latter configuration formsthe ground state of the boron atom in the high-field regimeγ>8.0251. Analogous calculations for the B+ givea sequence of the four following ground state configurations:1s22s2 (Sz = 0), 1s22s2p-1 (Sz = -1),1s22p-13d-2 (Sz = -1) and1s2p-13d-24f-3 (Sz = -2).The above series of groundstate configurations are extracted from the results of numericalcalculations for a number of electronic configurations selectedaccording to general energetical arguments.