Nonadiabatic relativistic correction in H2 , D2 , and HD

Abstract

We calculate the nonadiabatic relativistic correction to rovibrational energy levels of H2, D2, and HD molecules using the nonadiabatic perturbation theory. This approach allows one to obtain nonadiabatic corrections to all the molecular levels with the help of a single effective potential. The obtained results are in very good agreement with the previous direct calculation of nonadiabatic relativistic effects for dissociation energies and resolve the reported discrepancies of theoretical predictions with recent experimental results.

Ultrahigh finesse cavity-enhanced spectroscopy for accurate tests of quantum electrodynamics for molecules

“…In Table II and Fig. 3 (b), we show a comparison of our results with the recent theoretical value [2] and previous experimental results [10,11]. The difference between theory and our results is 2.3σ.…”

“…Molecular hydrogen, in the view of its simplicity, is well suited for testing quantum electrodynamics (QED) for molecules [1,2] as well as for searching for new physics beyond the Standard Model such as new forces [3] or extra dimensions [4]. Furthermore, molecular hydrogen possesses a wide structure of ultra-narrow rovibrational transitions [5] with different sensitivities to the proton charge radius and proton-to-electron mass ratio.…”

“…Furthermore, molecular hydrogen possesses a wide structure of ultra-narrow rovibrational transitions [5] with different sensitivities to the proton charge radius and proton-to-electron mass ratio. Therefore, the recent large progress in both theoretical [1, 2,6] and experimental [7][8][9][10][11] determinations of the rovibrational splitting in different isotopologues of molecular hydrogen makes it a promising system for adjusting several physical constants [12,13]. The most accurate measurements were performed for the HD isotopologue with absolute accuracy claimed to be 20 kHz [14] and 80 kHz [8] for the R(1) 2-0 line.…”

Precision measurement of the fundamental vibrational frequencies of tritium-bearing hydrogen molecules: T2, DT, HT

“…The transition frequencies of these weak lines are thus reported with a much higher uncertainty of 0.005 cm −1 . All measured transition energies are in very good agreement with the latest ab initio calculations based on NAPT theoretical framework 25,69 . This work demonstrates that measurements on tritiated species can be achieved at high accuracy, to within a factor of three compared to the accuracy for the nonradioactive species.…”

“…These methods were based on 20 , and separate approaches for adiabatic 21 and non-adiabatic 22 corrections, as well as computations of relativistic 23 and quantum electrodynamic effects 24 . This development has led to the comprehensive approach of nonadiabatic perturbation theory (NAPT) 25,26 , which now enables the rapid computation of all bound rovibrational states in the ground electronic manifold of the hydrogen isotopologues. In addition, and alongside, an even more refined and more accurate method involving direct 4-body calculations is being pursued, but this is currently limited to the computation of the binding energy of the lowest rovibrational level 27,28 .…”