A recent PISCES-B Mod experiment [Nishijima et al., J. Phys. B 43, 225701 (2010)] has revealed up to a factor of 5 discrepancy between measurement and the two existing theoretical models [Badnell et al., J. Phys. B 29, 3683 (1996); Bartschat et al., J. Phys. B 35, 2899 (2002)], providing important diagnostics for Mo i. In the following paper we address this issue by employing a relativistic atomic structure and $R$-matrix scattering calculations to improve upon the available models for future applications and benchmark results against a recent Compact Toroidal Hybrid experiment [Hartwell et al., Fusion Sci. Technol. 72, 76 (2017)]. We determine the atomic structure of Mo i using grasp${}^0$, which implements the multiconfigurational Dirac-Fock method. Fine structure energies and radiative transition rates are presented and compared to existing experimental and theoretical values. The electron-impact excitation of Mo i is investigated using the relativistic $R$-matrix method and the parallel versions of the Dirac atomic $R$-matrix codes. Electron-impact excitation cross sections are presented and compared to the few available theoretical cross sections. Throughout, our emphasis is on improving the results for the $z{}^{5}P_{1,2,3}^o\to a{}^{5}S_2,z{}^{7}P_{2,3,4}^o\to a{}^{7}S_3$ and $y{}^{7}P_{2,3,4}^o\to a{}^{7}S_3$ electric dipole transitions of particular relevance for diagnostic work.

• Received 30 July 2017

DOI:https://doi.org/10.1103/PhysRevA.96.042713