Multiconfiguration Hartree-Fock Breit-Pauli Results for the 2P exp 2 P/sub 1/2/ - 2P exp 2 P/sub 3/2/ E2 and M1 Transitions

摘要

Some forbidden transitions become possible through the fine structure splitting of an LS term into a series of J levels. Examples are the E2 and M1 transition between the 2p exp 2 P/sub 1/2/ and 2p exp 2 P/sub 3/2/ levels in the boron sequence. In the non-relativistic approximation, these levels are degenerate and there is a strong interaction between the 2s exp 2 2p and 2p exp 3 exp 2 P configurations, indicating important correlation efforts. Thus the theoretical determination of the fine structure splitting provides a sensitive test for a computational method. The MCHF method has been extended to include the relativistic corrections in the Breit-Pauli approximation. An MCHF-BP calculation proceeds in two stages. In the first, a non-relativistic MCHF calculation is performed to determine an orbital basis, whereas in the second the Breit-Pauli interaction matrix is diagonalized. At present the orbit-orbit interactions are neglected. Calculations have been performed with this method for 2p exp 2 P/sub 1/2/ - 2p exp 2 P/sub 3/2/ E2 and M1 transitions of the boron sequence. In order to study the effect of correlation outside the n = 2 complex, two sets of calculations were performed. In the first, the radial orbitals were determined for an MCHF calculation for (2s exp 2 2p, 2p exp 3 ) exp 2 P and the Breit-Pauli diagonalization was over the set of four configuration states, (2s exp 2 2p, 2p exp 3 exp 2 P, 2p exp 3 exp 2 D and 2p exp 3 exp 4 S). In the second, the MCHF calculation was for (2s exp 2 2p, 2p exp 3 , 2p exp 2 ( exp 1 S)3p, 2s exp 2 4p, 2s2p( exp 1 , exp 3 P) 3d, 2s3s( exp 3 S) 2p) exp 2 P and the Breit-Pauli diagonalization included twenty exp 2 P configuration states, as well as 2p exp 3 exp 2 D and 2p exp 3 exp 4 S, for a total of twenty-two configuration states. (ERA citation 07:062234)