  We report a systematic analysis of the performance of a widely used set of
Dirac-Fock pseudopotentials for quantum Monte Carlo (QMC) calculations. We
study each atom in the periodic table from hydrogen (Z=1) to mercury (Z=80),
with the exception of the 4f elements (57 <= Z <= 70). We demonstrate that
ghost states are a potentially serious problem when plane-wave basis sets are
used in density functional theory (DFT) orbital-generation calculations, but
that this problem can be almost entirely eliminated by choosing the s channel
to be local in the DFT calculation; the d channel can then be chosen to be
local in subsequent QMC calculations, which generally leads to more accurate
results. We investigate the achievable energy variance per electron with
different levels of trial wave function and we determine appropriate plane-wave
cutoff energies for DFT calculations for each pseudopotential. We demonstrate
that the so-called "T-move" scheme in diffusion Monte Carlo is essential for
many elements. We investigate the optimal choice of spherical integration rule
for pseudopotential projectors in QMC calculations. The information reported
here will prove crucial in the planning and execution of QMC projects involving
beyond-first-row elements.
