Based on recent advances in ab-initio methods, theoretical diatomic potential energy curves have been obtained that have yielded full vibration-rotation spectra with near-spectroscopic accuracy and generated information that has as yet been inaccessible to experimental spectroscopy. For the ground state of O2, the theoretical predictions provided 15% of the full spectrum. For the ground state of B2, they provided 85% of the full spectrum and led to a reassignment of electronic transitions. For the ground state of F2, a competition between quadrupole repulsion and dispersion forces was uncovered that creates a long range barrier. Obtaining such accuracy requires complete configuration interaction in the valence space. Essential for achieving this goal is a new method of extrapolating reliably to the full configuration interaction limit. It is based on recently discovered novel intrinsic scaling relations and it is effective for single states as well as for the simultaneous extrapolation of several states.

Theoretical potential energy curves ahead of spectroscopic potential energy curves

244th National Meeting (2012)

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