Real-space calculations of atomic and molecular polarizabilities using asymptotically correct exchange-correlation potentials

The static electric dipole polarizabilities for a variety of atoms and molecules are calculated using a finite-field method based on ab initio pseudopotential density functional theory. The calculations are performed in real space without an explicit basis. We employ different representations of the exchange-correlation potential: the local density approximation, generalized gradient approximation, and asymptotically corrected functionals introduced by van Leeuwen and Baerends and by Casida and Salahub. Our calculations show that the computed values of polarizabilities are strongly influenced by the asymptotic behavior of the density functional exchange-correlation potential. The accuracy of theoretical atomic and molecular polarizabilities is substantially improved by the use of asymptotically correct exchange-correlation functionals. This result can be explained in terms of electronic excitation energies and the polarizability sum rule.