Polarizability of Polymers Using One-Electron Self-Interaction-Corrected Density Functional Methods

The majority of density functional approximations (DFAs) incorrectly predict excessive polarization in conjugated polymers when subjected to an external electric field. This overpolarization by DFAs, which occurs due to the delocalization error, results in a significant overestimation of the static linear polarizability of the polymers. Herein, we use two one-electron self-interaction-correction methods, viz., the Perdew-Zunger self-interaction correction (PZSIC) and the locally scaled self-interaction correction (LSIC) method of Zope and co-workers, that explicitly remove one-electron self-interaction error to compute the static linear polarizability of polydiacetylene (PDA) and polybutatriene (PBT) oligomers. A comparison of predicted linear polarizabilities with benchmark CCSD(T)-F12 values shows that the PZSIC method significantly underestimates linear polarizabilities, which is the result of tightly bound valence electrons in PZSIC. The quasi-self-consistent LSIC method provides a very good description of the polarization effects in these polymers. When compared to the literature results for the GKS-spRPA, CPHF, LC-BLYP, HF, and RPA methods, the LSIC percent error is one of the two lowest for PBT and is the lowest for the PDA.