Is the adiabatic approximation sufficient to account for the post-Born–Oppenheimer effects on molecular electric dipole moments?

The infrared absorption spectrum of radioactive water isotopologue H215O

A room temperature line list for the H215O radioactive isotopologue of the water molecule is computed using the variational nuclear-motion DVR3D program suite and an empirical high-precision potential energy function. The line list consists of rotation-vibrational energies and Einstein-A coefficients, covering a wide spectral range from 0 to 25000 cm-1 and the total angular momenta J up to 30. Estimates of air-broadening coefficients are provided. Experimentally derived energies of H216O, H217O and H218O from the literature are used to provide improved energies for important states with uncertainty estimates for the H215O. A number of the wmost promising spectroscopic ranges for the detection of H215O are proposed. The calculated absorption spectrum should be useful for the study gaseous radioactive water at IR region, determining concentration, etc.

The electric dipole moments in the ground states of gold oxide, AuO, and gold sulfide, AuS

The B²Σ^- - X²Π_3/2(0,0) bands of a cold molecular beam sample of gold monoxide, AuO, and gold monosulfide, AuS, have been recorded at high resolution both field free and in the presence of a static electric field. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ→_el, of 2.94±0.06 D and 2.22±0.05 D for the X²Π_3/2(v = 0) states of AuO and AuS, respectively. A molecular orbital correlation diagram is used to rationalize the trend in ground state μ→_el values for AuX (X = F, Cl, O, and S) molecules. The experimentally determined μ→_el are compared to those computed at the coupled-cluster singles and doubles (CCSD) level augmented with a perturbative inclusion of triple excitations (CCSD(T)) level of theory.

Non-adiabatic effects in thermochemistry, spectroscopy and kinetics: the general importance of all three Born–Oppenheimer breakdown corrections

Analytical and numerical solutions describing Born–Oppenheimer breakdown in a simple, widely applicable, model depict shortcomings in modern computational methods.