g'day,

I need to calculate the heat of combustion of some novel compounds.

I first thought to calculate the heat of formation of both the compound plus oxygen, and then its oxidation productions (CO2, H2O, etc), and take the difference. I tried to do this using DMol3, but saw the message:

"DFT atomic data not found.

   No matching atomic binding energies in Thermo_Atom file

   Skipping heat of formation calculation"

This lead to this discussion on that message. To take the system discussed there of methane, would it be easier / quicker for me to consider the reaction:

  CH4  +  2 O2  -> CO2  +  2 H2O

then calculate the enthalpy of reaction as:

  dH (heat of combustion)  =  dH (CO2)  +  dH (H2O)  -  dH(CH4)  -  dH(O2)

Or are there some traps here I am not aware of ?

Thanks in advance

Mat