Density‐Based Description of Molecular Polarizability for Complex Systems

In this chapter, we have introduced a different approach to polarizability prediction in complex systems, which does not need solving the laborious coupled‐perturbed Hartree–Fock (CPHF) or Kohn–Sham (CPKS) equations. To make that happen, some simple density‐based functions from the information‐theoretic approach (ITA) are employed. We have verified that strong linear regression correlations exist between the polarizability and ITA quantities for various complex systems of both localized and delocalized electronic structures. Illustrative applications include predicting the polarizability of complex proteins and excited‐state systems. Intriguingly, combined with the linear‐scaling generalized energy‐based fragmentation (GEBF) method, one can predict the subsystem (of a few atoms or groups) polarizability based on the established linear regression equations, thus the total polarizability via a linear combination of subsystem polarizabilities for proteins. Overall, our computational results showcase that the GEBF‐ITA protocol should be a robust and cost‐effective theoretical tool in predicting molecular polarizabilities, especially when more advanced electronic structure methods are adopted.