Electrodynamic Response and Stability of Molecular Crystals
  We show that electrodynamic dipolar interactions, responsible for long-range fluctuations in matter, play a significant role in the stability of molecular crystals. Density functional theory calculations with van der Waals interactions determined from a semilocal "atom-in-a-molecule" model result in a large overestimation of the dielectric constants and sublimation enthalpies for polyacene crystals from naphthalene to pentacene, whereas an accurate treatment of non-local electrodynamic response leads to an agreement with the measured values for both quantities. Our findings suggest that collective response effects play a substantial role not only for optical excitations, but also for cohesive properties of non-covalently bound molecular crystals. 
Bohdan Schatschneider, Jian-Jie Liang, Anthony M. Reilly, Noa Marom,   Guo-Xu Zhang, Alexandre Tkatchenko
cond-mat.mtrl-sci physics.chem-ph