Hard numbers on soft matter

Graphitic systems are ideal examples of the soft-matter challenge for quantum mechanics that must account for both strong local atom bonds and weak nonlocal van der Waals interactions between atoms separated by empty space. Here a new density functional (DF), which encompasses nonlocal correlations among the electrons, is applied successfully to obtain structure, bonding, and compressibility, documenting the decisive role of the interlayer vdW interactions. The understanding emerging from this new extended-DF formulation has bearing on broad classes of problems, including surfaces, in physics, chemistry, biology, medicine, and technology, where we can now provide an efficient and accurate DF-theory account.