Accurate prediction of H3O+ and D3O+ sensitivity coefficients to probe a variable proton-to-electron mass ratio
Abstract
The mass sensitivity of the vibration-rotation-inversion transitions of H-3 O-16(+), H-3 O-18(+), and D-3 O-16(+) is investigated variationally using the nuclear motion program TROVE (Yurchenko, Thiel & Jensen). The calculations utilize new high-level ab initio potential energy and dipole moment surfaces.
Along with the mass dependence, frequency data and Einstein A coefficients are computed for all transitions probed. Particular attention is paid to the Delta vertical bar k vertical bar = 3 and Delta vertical bar k - l vertical bar = 3 transitions comprising the accidentally coinciding vertical bar J, K = 0, upsilon(2) = 0(+)> and vertical bar J, K = 3, upsilon(2) = 0(-)> rotation-inversion energy levels.
The newly computed probes exhibit sensitivities comparable to their ammonia and methanol counterparts, thus demonstrating their potential for testing the cosmological stability of the proton-to-electron mass ratio. The theoretical TROVE results are in close agreement with sensitivities obtained using the non-rigid and rigid inverter approximate models, confirming that the ab initio theory used in the present study is adequate.