Predicting the Post-Hartree‒Fock Electron Correlation Energy of Complex Systems with the Information-Theoretic Approach

To employ some simple physics-inspired density-based information-theoretic approach (ITA) quantities to appreciate the electron correlation energies is an unaccomplished and ongoing task. In this work, we expand the territory of the LR(ITA) (LR means linear regression) protocol to more complex systems, including (i) 24 octane isomers; (ii) polymeric structures, polyyne, polyene, all-trans-polymethineimine, and acene; (iii) molecular clusters, such as metallic Ben and Mgn, covalent Sn, hydrogen-bonded protonated water clusters H+(H2O)n, and dispersion-bound carbon dioxide (CO2)n, and benzene (C6H6)n clusters. With LR(ITA), one can simply predict the post-Hartree‒Fock (such as MP2 and coupled cluster) electron correlation energies at the cost of Hartree‒Fock calculations, even with chemical accuracy. For large molecular clusters, we employ the linear-scaling generalized energy-based fragmentation (GEBF) method to gauge the accuracy of LR(ITA). Employing benzene clusters as an illustration, the LR(ITA) method shows similar accuracy to that of GEBF. Overall, we have verified that ITA quantities can be used to predict the electron correlation energies of various complex systems.