Calculation of the parity- and time-reversal-violating interaction in ${}^{225}$RaO

The ten-electron generalized relativistic effective core potential and the corresponding correlation spin-orbital basis sets are generated for the Ra atom and the relativistic coupled-cluster calculations for the RaO molecule are performed. The main goal of the study is to evaluate the $T,P$-odd parameter $X$ characterized by the molecular electronic structure and corresponding to a “volume effect” in the interaction of the ${}^{225}$Ra nucleus Schiff moment with electronic shells of RaO. Our final result for $X{(}^{225}$RaO$)$ is $-7532$ which is surprisingly close to that in ${}^{205}$TlF but has a different sign. The obtained results are discussed and the quality of the calculations is analyzed. The value is of interest for a proposed experiment on RaO [Phys. Rev. A 77, 024501 (2008)] due to a very large expected Schiff moment of the ${}^{225}$Ra nucleus.