11.6.3 Iterative Approach for Supermolecular Properties

The iterative embedding method is a useful approach for the computation of supermolecular properties. ³⁷³ Ferino-Pérez A., Jagau T.-C.
J. Chem. Theory Comput.
(2025), 21, pp. 9376. Link The keyword for requesting an iterative embedding calculation is EMB_ITER. In this approach, different parts of a system are chosen as active fragment in subsequent embedding calculations. The property is then expressed as the sum of contributions from the individual fragments. The high-level calculation must be repeated for each fragment, but this is computationally cheaper than treating the entire system at once.

It is possible to compute supermolecular static polarizabilities using the iterative embedding method. Within this approach, an element ${\alpha }_{xy}$ of the polarizability tensor $\alpha$ is computed as

where the sum over active fragments A includes the entire system. This method can also be used to compute supermolecular dipole moments. A component ${\mu }_x$ of the dipole moment vector $\mu$ is obtained as

The keywords for triggering these features are EMB_POL and EMB_DIPOLE, respectively.