Rovibrational energies of the hydrogen molecule in the electronic ground state derived from its vacuum ultraviolet (VUV) spectrum

Description
The dataset contains the term energies of the hydrogen molecule in its electronic ground state (3rd column) expressed as a function 
of the rotational (2nd column) and vibrational (1st column) quantum numbers  J and v relative to the ground level, v=0 and J=0, 
divided by hc, i.e. the product of Plancks constant h and the velocity of light c. These data are used to obtain ideal gas 
properties of hydrogen, e.g. its specific heat capacity, by the direct summation technique.

Source
The values of EvJ_(v,J) are derived from an analysis of the vacuum ultraviolet (VUV) spectrum of the hydrogen molecule. 
Primary source is the Paris Observatory MOLAT (atomic and molecular) database, which is freely accessible online (molat.obspm.fr). 
The button VUV Spectra of Small Molecules and then the first entry denoted Atlas of the VUV Emission Spectrum of H2 (78.6-171.3 nm) 
lead from the homepage to the original data.

Description of the scource
The spectrum contains 12265 lines including impurity and reference lines. The primary data for the current study are the wavenumbers 
(in cm-1) and the assignments, i.e. the specifications of initial and final states of the corresponding transition, of the H2 lines.
In particular, the current analysis is based on transitions between the vibrational ground state and the nine lowest vibrationally 
excited states of the lowest electronically excited state of the hydrogen molecule and its electronic ground state (Lyman band), which 
amounts to 4672 observed transitions. From these 4672 transitions the splittings of the rovibrational levels of the electronic ground 
state are derived by taking averages over equivalent differences. An exception are the three lowest rotational and the two lowest 
vibrational splittings which have been obtained from all available transition energies. The level splittings are then used to compute 
the term energy values by summation.

Accuracy
The accuracy of the data is roughly 1 cm-1. This estimate is based on the variation of the observed values for identical splittings. 
This absolute value corresponds to a relative accuracy of 0,01 % for the original VUV data. However, for the splittings of interest 
in the present study the relative accuracy amounts to 0,1 % for vibrational and to around 1 % for rotational splittings.
