Ionization potential and excitation energy calculations for ${\mathrm{Ba}}^{+}$ using the relativistic coupled-cluster method

We report the results of our relativistic coupled cluster singles, doubles, and partial triples calculations of the ionization potentials (IP) and excitation energies (EE) for different low-lying levels of ${\mathrm{Ba}}^{+}$. The accuracies of the IP’s and EE’s are approximately 0.2% and 1%, respectively. The inclusion of the triple excitations were crucial to achieve this degree of precision.