Good news, the article “On the breakdown of the Born–Oppenheimer approximation in LiH and LiD” has just been published in Journal of Physics: Condensed Matter.
The experimental study conducted in the 1990s on LiH/LiD suggested a breakdown of the Born-Oppenheimer approximation in this materials. Here we study these systems theoretically, treating the nuclei quantum mechanically, and compute electron densities beyond the strict Born–Oppenheimer approximation. This approximation is assumed, for instance, in conventional DFT, where the nuclei are treated as classical point-like particles.
Highlights:
• Beyond strict Born–Oppenheimer electron densities for LiH and LiD using density functional methods.
• Significant corrections to the electron density around nuclear equilibrium positions when quantum nuclear effects are included.
• We find improved agreement with experiment, but there remain interesting discrepancies between experimental and computational results that cannot be explained, for instance, by differences in the density functionals used.
If you are interested in quantum nuclear effects and related topics, you can read the paper (open access): https://doi.org/10.1088/1361-648X/ae3a2c