This is the question. From my logic, the best speed up is when use the
neutral system wfc set, and the density is constructed with this wfcs,
but using the correct number of electrons to the charged system, then
this density is the density for the freezed neutral system plus the
substraction/addition electrons to charge the system (the orbital density).
How can i do this? Is this a good idea?
I propound this, because the 3 cases for starting commands are not the
best approach to charged systems.
If you do the initial and the second calculation with the same number of
bands (set nbnd by hand) the approach could work, although I'm not sure
what the code would do in practice.
However, from my experience, the speedup of this kind of tricks is
usually negligible with respect to the human time spent setting thing
up. The reason is that convergence is usually exponential i.e. at each
iteration the accuracy is multiplied by a factor (hopefully <1) which is
more or less constant. Even if you start with a better guess, you may
only save a couple iterations
hth
--
Lorenzo Paulatto - Paris
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