bond-dissociation enthalpy

symbols: ${\rm{D}}H^{\circ}$, $\Delta_{\rm{diss}} H^{\circ}$, unit: $\pu{kJ mol-1}$

https://doi.org/10.1351/goldbook.08146

Standard molar enthalpy required to break a given bond of some specific molecular entity by homolysis.

Example: For $\ce{CH4 -> CH3. + H.}$, the bond-dissociation enthalpy is symbolized as ${\rm{D}}H^{\circ}(\ce{CH3-H})$.

Note: Although ${\rm{D}}H^{\circ}$ is commonly used, $\Delta_{\rm{diss}} H^{\circ}$ is more consistent with the notation for other thermodynamic quantities.

Source:
PAC, 2022, 94, 353. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)' on page 372 (https://doi.org/10.1515/pac-2018-1010)