Energy levels, radiative rates and electron impact excitation rates for transitions in Be-like Ti XIX

We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in Be-like Ti XIX. The general-purpose relativistic atomic structure package is adopted for calculating energy levels and radiative rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R -matrix code ( darc ) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 98 levels of the n ⩽ 4 configurations. Additionally, theoretical lifetimes are listed for all 98 levels. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 10 7.7 K. Comparisons are made with similar data obtained from the flexible atomic code ( fac ) to highlight the importance of resonances, included in calculations with darc , in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac , particularly for forbidden transitions, are also discussed.