CCL: Binding free energy from QM/MM Calculation for Ligand Protein complex

 Sent to CCL by: "Muhammad  Shabbir" [agri_chemist.]^[.yahoo.com]
 Dear Colleagues,We want to calculate binding free energy of Ligand-Protein
 complex. After completing QM/MM run we got following energies for
  complex:----------here Ligand]^[B3LYP/6-31G* and protein]^[UFF=qeq
 -------------
 UFF calculation of energy.
 Energy=  0.453152500   NIter=  0.
 Dipole moment=   -1.265215    2.913698   -3.244704
 ONIOM: saving gridpoint 1
 ONIOM: restoring gridpoint 3
 ONIOM: calculating energy.
 ONIOM: gridpoint 1 method: low  system: model energy:   0.453152500428
 ONIOM: gridpoint 2 method: high system: model energy: -1573.304203057569
 ONIOM: gridpoint 3 method: low  system: real energy:  23.105333051841
 ONIOM: extrapolated energy =  -1550.652022506156
 ONIOM: calculating electric field derivatives.
 ONIOM: Integrating ONIOM file 4 number  619
 ONIOM: Dipole    = 3.51466451D+00 7.85225957D+00 6.59929946D+00
 ONIOM: Dipole moment (Debye):
   X=   8.9334  Y=  19.9585  Z=  16.7737 Tot=  27.5591
 ------------------------
 My question is how to get binding free energy from these values? or is there
 need to run ligand and protein separately on QM and MM levels also as in
 complex?Any information on working equations for QM?MM binding free energy
 calculation will be greatly appreciated!!
 Dr.Shabbir