| 1:19:14 PM PDT - Tue, May 27th 2014 |
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The corrected energy is the total energy of the HF dimer system after correcting for basis set superposition error. The supermolecular energy is the total energy of the HF dimer system before corrections for basis set superposition error. Both the corrected and uncorrected values are for the full energy of the HF dimer system, from a reference point of "complete separation of nuclei and electrons." If you want to calculate a quantity that can be interpreted as the hydrogen bond energy between the two HF molecules, you need to add up the energy of the two HF monomers calculated in isolation (this is present earlier in your output file, look for the lines that start Total DFT energy = -99...., use the monomer energies from the calculations that didn't include ghost atoms) and subtract that sum from the corrected full-system energy of 199.465486362562 Hartree. That gives a very small number that, converted from Hartree to kcal/mol, looks to be in the right ballpark for hydrogen bond strength.
There is more work to be done to determine if this sample procedure provides a general template you could use to calculate hydrogen bonding between pairs of molecules. Is the DFT approach used here generally and sufficiently accurate? Do you need experimental geometry as an input, or can you generate appropriate system geometries? These easy questions could take a staggering effort to answer without reading prior research. I presume that you have access to an academic library where you can perform a literature search on topics like quantum chemical modeling of hydrogen bonding. If you do not have access to a good library system, try running queries on Google Scholar. A fair number of famous/prominent papers on a specific subtopic will be hosted publicly somewhere and Google Scholar can guide you to them even if your library does not subscribe to the originating journal. That's how I found the paper on BSSE counterpoise correction that is cited by the NWChem manual. If you are trying to use an NWChem feature that you haven't used before, note what papers the software authors cited and track them down so you can understand better. Try to find related review articles as well so you can get a sense for the surrounding context of the methodology and research questions without trying to personally synthesize it from dozens of more focused papers.
Good luck with your research!
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