Broken scaling laws of the transition probabilities from jj to LS coupling transitions

Abstract

Accurate electromagnetic transition rates between the ground electronic configurations are important in diagnostic studies of planetary nebulae. Based on a “quasi-complete basis” set, we present large-scale multi-configuration Dirac–Fock calculations of the forbidden transition rates within the ground electronic configuration along the nitrogen-like isoelectronic sequence. The broken scaling laws of the transition probabilities from jj to LS coupling transitions are elucidated and found to be extensions of the well-known scaling laws discussed in the single electron case. The equivalent oscillator strength is very large for ions in high-Z regions and should play a crucial role in the cooling mechanism in astrophysics. • We did an MCDF calculation of forbidden transition rates between the lowest 5 states of N-like ions. • The broken scaling laws of the transition rates from jj to LS coupling transition are elucidated. • These scaling laws are an extension of the scaling laws discussed in the single electron picture. • The equivalent oscillator strength of forbidden transitions will be very large for high-Z ions. • These transitions of high-Z ions should be important cooling mechanisms of the relevant plasmas.