Energy partitioning scheme based on self-consistent method for subsystems: populational space approach.

The refinement of the previously proposed energy partitioning scheme, self-consistent charge and configuration method for subsystems (Korchowiec and Uchimaru, J Chem Phys 2000, 112, 1623), is proposed. Our new realization takes rigorously into account all the interactions between subsystems and guarantees proper symmetry of the intermediate wavefunctions. In addition, the scheme is supplemented with natural orbitals for chemical valence to trace the charge reorganization during polarization and charge transfer steps. The water dimer and ammonia borane are used to illustrate the proposed formalism.