https://doi.org/10.1351/goldbook.H02748
Atomic fundamental physical constant used as @[email protected] of energy: \(E_{\text{h}}=\frac{\mathrm{\hslash }^{2}}{m_{\text{e}}\ a_{0}^{2}} = 4.359\ 7482(26)\times 10^{-18}\ \text{J}\), where \(\mathrm{\hslash}\) is the @[email protected] divided by \(2\ \pi \), \(m_{\text{e}}\) the @[email protected] and \(a_{0}\) the @[email protected]