[gmx-developers] DD support in ASPC

[Tomáš Trnka]

> I guess the history must be built up at the beginning of the run.

Yes, that's how it's done currently.

> So how about resetting the history for each particle if it moves to
> another processor, but storing it otherwise?

IMHO this is not the way to go - detecting that the shell has moved elsewhere 
seems to be the hard part of the problem. When we know that it has moved, we 
can easily pass the history along.

> That will lose some performance obviously.

Worse than that. Losing history will impact energy conservation (at least in 
the current implementation). In the ASPC method it's the predictor that 
guarantees good energy conservation. If the predictor is unable to work 
properly due to missing history, the code would need to switch to iterating 
the SCF solution to a high precision to keep reasonable energy conservation 
(could be done, but will impact the performance a lot if this happens every 
~20 steps).

2T