Density functional study of crystalline polyethylene

Density functional calculations have been performed for single chains and the crystalline (orthorhombic) form of polyethylene (PE). The geometrical structures are optimized without constraints, and the exchange-correlation energy is calculated using local density (LD) and non-local (gradient-corrected, GC) approximations. Both give good descriptions of the structure of a single PE chain, but LD calculations overestimate the binding energies between chains, and GC calculations lead to no interchain binding at all.