  Density functional approximations are known to significantly overestimate the
polarizabilities of long chain-like molecules. We study the static electric
dipole polarizabilities and the vertical ionization potentials of polyacenes
from benzene to pentacene using the Fermi-L\"owdin orbital based
self-interaction corrected (FLOSIC) density functional method. The
orbital-by-orbital self-interaction correction corrects for the overestimation
tendency of density functional approximations. The polarizabilities calculated
with FLOSIC-DFA are however overly corrected. We also tested the recently
developed locally-scaled self-interaction correction (LSIC) method on the
polyacenes. The local-scaling method applies full SIC in the one-electron
regions and restores the proper behavior of the SIC exchange-correlation
functionals in the uniform density limit. The results show that LSIC removes
the overcorrection tendency of the FLOSIC-DFA and produces results that are in
excellent agreement with reference CCSD values. The vertical ionization
potentials with LSIC also show good agreement with available experimental
values.
