Molecular Energy Decompositions in the Hilbert-Space of Atomic Orbitals at Correlated Level

This work describes a new model to partition the molecular energy into one- and two-center contributions in the Hilbert-space of atomic orbitals at correlated level. Our proposal makes explicit use of the pairing nature of chemical bonding phenomena to accommodate appropriately the correlation effects within these contributions. The model is based on the treatment of the kinetic energy as contributing to both one- and two-atom terms, according to the pairing or unpairing character of the electron cloud, and on the appropriate assignment of the density cumulant dependent contributions. Numerical results for selected systems are reported and compared with those arising from other models, showing the reliability of our predictions.