Improved partition functions for neutral and singly ionized uranium

Abstract

We have computed partition functions for neutral and singly ionized uranium (U I and U II) between 100 and 15 000 K. Energy-level values were obtained from ab initio atomic-structure calculations based on the Slater-Condon theory. The single-configuration approximation was used to define levels for 21 U I and 16 U II configurations. Partition functions for U I and U II are tabulated as a function of temperature, and comparisons are made with those obtained using observed levels. We present estimates of the uncertainty of the tabulated partition functions.