Knowledge Bank

Rather than computational spectroscopy that implies a qualitative treatment relying on visual observations of spectra, we apply {\em computational spectrometry}}}, 253 317 (2005)} to achieve a quantitative reproduction of precise data from spectra measured with electronic instruments. For spectra involving pure rotational and vibration-rotational transitions of diatomic molecules, even full isotopic substitution for spectra measured in the absence of applied magnetic fields fails to provide sufficient data to enable a complete evaluation of parameters for all of potential energy, adiabatic, and nonadiabatic rotational and vibrational effects, even omitting nuclear field shifts that might be neglected for light atomic centres. We hence calculate, for internuclear distances over a broad range, the rotational g factor, which measurements of the Zeeman effect on vibration-rotational transitions over a large range of quantum numbers $v$ and $J$ might in principle produce but which has never been accomplished in practice. Applying this information in constrained fits of spectral data, we evaluated the remaining parameters, for instance for H$2$}}, 1747 1758 (2005)}, HeH$+$}}, 319 334 (2005)} and NaCl}}, 632 639 (2005)}. Combined with an algebraic approach based on the most highly developed effective hamiltonian}}, 187 215 (1998)}, this procedure yields the most physically meaningful conventional parameters.