  Pulay's Residual Metric Minimization (RMM) method is one of the standard
techniques for achieving self consistency in ab initio electronic structure
calculations. We describe a reformulation of Pulay's RMM which guarantees
reduction of the residual at each step. The new version avoids the use of
empirical mixing parameters, and is expected to be more robust than the
original version. We present practical tests of the new method implemented in a
standard code based on density-functional theory (DFT), pseudopotentials, and
plane-wave basis sets. The tests show improved speed in achieving self
consistency for a variety of condensed-matter systems.
