how to calculate the interaction energy between ligand and protein


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I used QM\MM method to optimize the protein-ligand complex. protein was in the MM region and ligand is in the QM region. After optimization, I want to how to calculate the interaction energy between ligand and protein. (include the electrostatic and van der Waals interaction energies) Is anyone can help me?

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Given the standard output

------------------------------------------------------------------------
QM/MM Energy
------------------------------------------------------------------------
quantum energy -537.200184022 (-.141042E+07 kjoule/mol)
quantum energy adjusted -537.200184022 (-.141042E+07 kjoule/mol)
quantum energy internal -537.135248946 (-.141025E+07 kjoule/mol)
Bq-nuclear energy 3.733295197 (0.980177E+04 kjoule/mol)
Bq-electron energy -3.798230274 (-.997225E+04 kjoule/mol)
classical energy -16.117550021 (-.423166E+05 kjoule/mol)
total qmmm energy -553.317734044 (-.145274E+07 kjoule/mol)
------------------------------------------------------------------------

the electrostatic interaction energy can be calculated as sum of "Bq-nuclear energy" and "Bq-electron energy", or as a difference between
"quantum energy" and "quantum energy internal". Vdw interaction energy and others ( e.g. bonded, etc) are unfortunately buried in the "classical energy" term. Please note that a single interaction energy number would likely be meaningless.


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