Dispersion coefficients for van der Waals complexes, including C60-C60

A previously proposed and tested [Phys. Rev. Lett. 76, 102 (1996), Phys. Rev Lett. 77 2029 (1996)] van der Waals density functional is applied to van der Waals complexes. Dynamic polarizabilities, alpha(iu), and dispersion coefficients, C-6, are obtained with a useful accuracy and at a low computational cost using ground-state electron densities as input. We compare results for C-6 for small and medium-sized molecules with existing results obtained using more cumbersome methods. The computational simplicity of the functional opens up the possibility to treat large systems of real interest within different fields of physics, chemistry and biology. This is illustrated by the application to C-60 We present results for the static polarizability alpha(0) and the dispersion coefficient C-6 for two such molecules.