sending and receiving of beads

[Elliot Menkah]

Hello everyone,

I would like to know how the beads are sent from i-PI to the client code please. 

Are they sent together as a 1D array when u set nbeads=N under <initialize> tag or they're sent in batches? If any of the two can be achieved, what controls the choice?  

I'm using ipi version 1.0 and interfacing it with ONETEP. 

Thank you. 

[Nicolas Künzel]

Hi,

as I got it from the documentation and so on I-PI just sents the positions of one bead to the client code, gets the forces, than send the next bead.
So the client code just takes the bead as a "normal" atom and calculates the forces only for that bead.

[Michele Ceriotti]

Exactly. One bead at a time - we thought for a while about making it possible to send batches, but would require deep changes to the infrastructure. Also,

in general when doing ab initio it is better to use a separate ab initio code for each bead, as it extrapolates WFC much better in time than across the ring polymer.

Finally, please use the -dev version of i-PI, we have diverged so much from v1.0 that we'll not be able to help you much if you need something. A v 2.0 is

in the making. 

[Elliot Menkah]

thank you Nicolas

[Elliot Menkah]

ok, thank you Michele.