CHEMICAL HARDNESS, LINEAR-RESPONSE, AND PSEUDOPOTENTIAL TRANSFERABILITY

We propose a systematic method of analyzing pseudopotential transferab ility based on linear-response properties of the free atom, including self-consistent chemical hardness and polarizability. Our calculation of hardness extends the approach of Teter not only by including self-c onsistency, but also by generalizing to nondiagonal hardness matrices, thereby allowing us to test for transferability to nonspherically sym metric environments. We apply the method to study the transferability of norm-conserving pseudopotentials for a variety of elements in the P eriodic Table. We iind that the self-consistent corrections are freque ntly significant, and should not be neglected. We prove that the parti al-core correction improves the pseudopotential hardness of alkaline m etals considerably. We propose a quantity to represent the average har dness error and calculate this quantity for many representative elemen ts as a function of pseudopotential cutoff radii. We find that the ato mic polarizabilities are usually well reproduced by the norm-conservin g pseudopotentials. Our results provide useful guidelines for making o ptimal choices in the pseudopotential generation procedure.