<i>Ab initio</i> calculations of the spectrum of lawrencium

We present high-accuracy relativistic investigations of the spectrum Lr, element 103, prompted by planned optical spectroscopy experiments on this rare and short-lived atom. Reliable predictions transition lines are important for planning success these challenging measurements. The coupled cluster approach was used to calculate energies lowest excited states, while combination configuration-interaction method with many-body perturbation theory employed address higher-lying states obtain strengths lifetimes levels experimental interest. performed similar calculations Lu, lighter homologue where data available. For element, both calculated Einstein coefficients in excellent agreement previously measured values, confirming accuracy reliability our Lr.