Each .ls file contains a number of transition properties including: Atomic weight, principal quantum number, energies of initial and final states, transition energies, wavelength in vacuum, wavelength air, type of transition, line strengths, gf values, transition rates:
Format of an LS transition: ##### Transition between files: E O Z = 9 n = 7 3 -97.50578137 2s(2).2p(3)2P1_2P 3 -96.52277315 2s.2p(4)3P2_2P 215739.13 CM-1 463.52 ANGS(VAC) 463.52 ANGS(AIR) E1 length: S = 7.81694D-01 GF = 5.12259D-01 AKI = 2.65057D+09 velocity: S = 8.22227D-01 GF = 5.38822D-01 AKI = 2.78801D+09 ##### An LSJ transition: ##### 1 -74.36649804 2s(2).2p(3)2P1_2P 1 -73.65565658 2s.2p(4)1S0_2S 156006.31 CM-1 641.00 ANGS(VAC) 641.00 ANGS(AIR) E1 S = 4.69243D-01 GF = 2.22364D-01 AKI = 1.80493D+09 4.68123D-01 2.21833D-01 1.80062D+09 .....
The convergence of the length and velocity forms are important factor for estimating the accuracy of the model. The Breit-Pauli methods have not modified the transition operator for the lowest order relativistic corrections in the velocity form. These are not important for the allowed transitions, but are important in spin-forbidden transitions. Generally, the accuracy of a transition depends on the accuracy of the length and velocity form in the non-relativistic approximation, and the accuracy of the Breit-Pauli transition energy, with the normalized length form value preferred. For intercombination transition, accuracy also depends on other factors, such as the accuracy of the separation of the two terms important for the transition.