Improving the RMM-DIIS eigensolver

Who:Jens Jørgen

Currently, our RMM-DIIS eigensolver will always take two steps for each state. In an attempt to make the eigensolver faster and more robust, we should investigate the effect of taking a variable number of steps depending on the change in the eigenstate error and occupations number as described in [Kresse].

[Kresse]G. Kresse, J. Furthmüller: Phys. Rev. B 54, 11169 - 11186 (1996) “Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set”

Any potential improvements in algorithms need to be evaluated on a large set of systems. The SCF Convergence Evaluation page is dedicated to presenting those evaluations.