Bijaya Pathak

Yes, ONIOM calculations are different from the normal Gaussian calculations. Normal Gaussian calculations covers only DFT part whereas ONIOM includes both DFT as well as force-field calculations.

I can elaborate the answer if you share your output file.

ONIOM is a subtractive QM/MM method. The output file prints the various components of the calculation, and then the final energy:

ONIOM: gridpoint 1 method: low system: model energy: 0.018351373282

ONIOM: gridpoint 2 method: high system: model energy: -229.414938123056

ONIOM: gridpoint 3 method: low system: real energy: 0.024899833916

ONIOM: extrapolated energy = -229.408389662421

If you want to report the ONIOM energy, then you would take the final value above. If you have performed an optimization you could search (or grep) for the last occurence of this line "extrpolated energy" in your output file.

If you have performed a frequency calculation and you want to report the thermochemical values, then these are printed in exactly the same way as a QM-only calculation:

Sum of electronic and zero-point Energies= -229.275751

Sum of electronic and thermal Energies= -229.271023

Sum of electronic and thermal Enthalpies= -229.270079

Sum of electronic and thermal Free Energies= -229.304356

These terms already include the "ONIOM: extrapolated energy" value from above.

If you want to grab these terms quickly from the command line for multiple files, then feel free to check out our python tool goodvibes (conda install -c patonlab goodvibes) which will do exactly that.

Happy ONIOM-ing!

Please look this ----

http://schlegelgroup.wayne.edu/Software/oniomtoolTAO/TAOtutorial.html