Numerical grids for density functional calculations of molecular properties

There is an increasing number of applications using methods based on density functional theory (DFT) describing a large variety of systems of chemical interest. All these calculations are performed through evaluations of integrals of exchange and correlation contributions to the energy and the potential, which depend on the density and also on its first and second derivatives (nonlocal functionals). Within our DF program, the integrand is decomposed into single-center components, through the introduction of weight functions, and its radial and angular dependence can be chosen. In this article, we give a brief description of these features, with compared performances of different grids for the evaluation of different integrals, such as the total number of electrons and the exchange and correlation energies. More complex properties, such as total energies and equilibrium geometries, are also studied with respect to the choice of the grid of points, in order to determine the most favorable radial and angular quadrature schemes. The incidence of this choice is analyzed in the case of the metal–metal bond of the Ru₂, Rh₂, and Pd₂ dimers. Finally, the use of an extended grid of points is shown necessary for systems involving weak interactions, such as the Ar₂ molecule. © John Wiley & Sons, Inc.