Chou has recently presented an approximation to the norm-conserving form of Vanderbilt’s nonlocal Hermitian pseudopotential. We point out two minor shortcomings of the Chou approximation and also show that it is actually easier to construct the Vanderbilt pseudopotential than to construct Chou’s approximation to it. The all-electron silver d-electron logarithmic derivative is compared over a range of energies with that obtained from a Vanderbilt pseudopotential which is exact at two energies and with Chou’s approximate pseudopotential. The agreement with the former is excellent and with the latter is only fair.

• Received 30 July 1992

DOI:https://doi.org/10.1103/PhysRevB.47.6728