quantized internal energy

The quantized internal energy of a molecule in its electronic ground or excited state can be approximated with sufficient accuracy for analytical purposes by:

$E int = E el + E vib + E rot$

where $E el$ is the electronic, $E vib$ the vibrational and $E rot$ the rotational energy, respectively.

Source:

PAC, 1988, 60, 1449 (Nomenclature, symbols, units and their usage in spectrochemical analysis - VII. Molecular absorption spectroscopy, ultraviolet and visible (UV/VIS) (Recommendations 1988)) on page 1452