Straightforward ab initio calculation of enthalpies of combustion and formation of hydrocarbons

Ab initio calculation of enthalpies of combustion and formation of hydrocarbons has been carried out directly from the well-known equation of combustion. This calculation has been established to give a high accuracy comparable with that obtained in the calculations from isodesmic or homodesmotic reactions. The calculation scheme includes a three-exponent basis set with polarization functions, electron-correlation and thermochemistry corrections. Hydrocarbons of various structures such as linear molecules, strained and unstrained carbon cycles, molecules with double bonds and others are considered.