Highly accurate HF dimer {\it ab initio} potential energy surface

A very accurate, (HF)$_2$ potential energy surface (PES)is constructed based on \ai\ calculations performed% at the CCSD(T) level of theory with an aug-cc-pVQZ-F12basis set at about 152~000 points.A higher correlation correction is computed at CCSDT(Q) level for 2000 points and is considered alongside other more minorcorrections due to relativity, core-valence correlation and Born-Oppenheimer failure.The analytical surface constructed uses 500 constants to reproduce the \ai\ points with a standard deviation of 0.3 \cm.Vibration-rotation-inversion energy levels of the HF dimer are computed for this PES by variational solution of the nuclear-motionSchr\"{o}dinger using program WAVR4. Calculations over an extended range of rotationally excited states show very good agreementwith the experimental data. In particular the known empirical rotational constants $B$ for the ground vibrational states are predicted to better than about 2 MHz.$B$ constants for excited vibrational states are reproduced several times more accurately than by previous calculations. %The experimental dissociation energy of the HF dimer is reproduced \ai\ within the experimental accuracy of about 1 \cm\ for the first time. This level of accuracy is shown to extend to higher excited inter-molecular vibrational states $v$ and higher excited rotational quantum numbers $(J,K_a)$

ExoMol line lists – LI. Molecular line lists for lithium hydroxide (LiOH)

New molecular line lists for lithium hydroxide (6Li16O1H and 7Li16O1H isotopologues) covering wavelengths λ > 1 μ m (0–10 000 cm−1 range) are presented. Each line list contains around 300 million transitions between rotation–vibration energy levels with total angular momentum up to J = 95, applicable for temperatures up to T ≈ 3500 K. Line list calculations were based on a previously published, high-level ab initio potential energy surface and a newly computed dipole moment surface of the ground X~1Σ+ electronic state. Lithium-containing molecules are important in a variety of stellar objects and there is potential for LiOH to be observed in the atmospheres of exoplanets. Transit spectra are simulated using the rocky super-Earth 55 Cancri e as an example with two different atmospheric scenarios including LiOH. This work provides the first, comprehensive line lists of LiOH to facilitate its future molecular detection. The OYT7 line lists along with the associated temperature- and pressure-dependent molecular opacities can be downloaded from the ExoMol database at www.exomol.com and the CDS astronomical database

ExoMol line lists -- LI. Molecular line list for lithium hydroxide (LiOH)

A new molecular line list for lithium hydroxide ($^{7}$Li$^{16}$O$^{1}$H) covering wavelengths $\lambda > 1 \mu$m (the 0-10000 cm$^{-1}$ range) is presented. The OYT7 line list contains over 331 million transitions between rotation-vibration energy levels with total angular momentum up to $J=95$ and is applicable for temperatures up to $T\approx 3500$ K. Line list calculations are based on a previously published, high-level \textit{ab initio} potential energy surface and a newly computed dipole moment surface of the ground \tilde{X}\,^1\Sigma^+ electronic state. Lithium-containing molecules are important in a variety of stellar objects and there is potential for LiOH to be observed in the atmospheres of exoplanets. This work provides the first, comprehensive line list of LiOH and will facilitate its future molecular detection. The OYT7 line list along with the associated temperature- and pressure-dependent opacities can be downloaded from the ExoMol database at www.exomol.com and the CDS astronomical database

Experimental Confirmation of Quantum Monodromy: The Millimeter Wave Spectrum of Cyanogen Isothiocyanate NCNCS

We have made energy-momentum maps for the experimental end-over-end rotational energy and the two-dimensional bending vibrational energy, both of which confirm the dominating effects of nontrivial quantum monodromy in cyanogen isothiocyanate. Accidental resonances in the rotational spectra yield accurate intervals between bending states