We have used the DC-DFT technique to study the energy landscape of several conjugated organic molecules, as well as the relative polymorph energies in the crystalline phase. These are challenging problems due to the appearance of multiple low-energy conformers (and corresponding low-energy polymorphs), and self-consistent DFT calculations with standard semilocal and hybrid functionals fail to reproduce benchmark ab initio results. We attribute this to SIE, in the particular form of πdelocalization error as the degree of conjugation is tuned by means of various intramolecular torsion angles. Application of DC-DFT, using the same common functionals, significantly mitigates the errors in most cases and usually results in the correction energetic ordering of crystal polymorphs, when computed by means of a monomercorrection scheme 26 applied to a periodic DFT calculation.