Gaussian pseudopotentials with nonlinear core corrections for chemical accuracy

During the last decades, density functional theory (DFT) has proven its pivotal role for computational studies in the fields of condensed matter physics and quantum chemistry. Particularly the Kohn-Sham formalism (KS) of DFT has gained enormous popularity as an ab initio method applicable to relatively large systems. An essential ingredient for many large scale implementations of KS-DFT are pseudopotentials which are also frequently denoted as effective core potentials. \nAdding a non-linear core correction (NLCC) to the well established Dual Space Gaussian type pseudopotentials, new pseudopotentials are constructed for the Perdew Burke Ernzerhof (PBE) functional. These potentials exhibit impressive features of transferability and accuracy of the results, without increasing the hardness of the pseudoatom, and they are benchmarked with respect to highly precise all-electron results of different physical and chemical quantities. The error introduced by pseudopotential approximation is sensibly lower than the one given by any small or medium size Gaussian basis sets in an all-electron calculation. Our results show that, when combined with systematic basis sets, norm-conserving pseudopotential calculations can be as accurate as all-electron calculations.