title: Oscillations in meta-generalized-gradient approximation potential energy surfaces for dispersion-bound complexes.
abstract: Meta-generalized-gradient approximations (meta-GGAs) in density-functional theory are exchange-correlation functionals whose integrands depend on local density, density gradient, and also the kinetic-energy density. It has been pointed out by Johnson et al. [Chem. Phys. Lett. 394, 334 (2004)] that meta-GGA potential energy curves in dispersion-bound complexes are susceptible to spurious oscillations unless very large integration grids are used. This grid sensitivity originates from the saddle-point region of the density near the intermonomer midpoint. Various dimensionless ratios involving the kinetic-energy density, found in typical meta-GGAs, may be ill-behaved in this region. Grid sensitivity thus arises if the midpoint region is sampled by too sparse a grid. For most meta-GGAs, standard grids do not suffice. Care must be taken to avoid this problem when using, or constructing, meta-GGAs.
authors.affiliation: Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Erin R
authors.initials: ER
authors.lastname: Johnson
authors.forename: Axel D
authors.initials: AD
authors.lastname: Becke
authors.forename: C David
authors.initials: CD
authors.lastname: Sherrill
authors.forename: Gino A
authors.initials: GA
authors.lastname: DiLabio