Cover Image, Volume 113, Issue 18

Poly(3‐hexylthiophene) is one of the most widespread conjugated polymers for organic electronics applications. Yet none of the atomistic models proposed for its crystal structure is fully satisfactory from a quantitative standpoint. Although the effect of the aliphatic side chains on crystal packing is now clear, it is common practice in theoretical investigations to approximate them to a rigid, fully extended arrangement or to shorten/remove them completely. In the cover article by Antonino Famulari et al. on page 2154 , the conformational problem of a hexyl residue is tackled by quantum mechanical means without any a priori assumption but steric packing constraints.