[ESPResSo-devel] About "blockfile read auto" with multiple nb interaction

[Mingyang Hu]

Dear all,

I came across this situation recently:

In a simulation system, there is more than one non-bonded interactions between particle type 1 and 2, e.g. BOTH Lennard Jones and LJ-Cos2. So when a checkpoint file is written, the interaction block has a line of the following form:

{ 1 1 lennard-jones ...some_lj_parameters... lj-cos2 ...some_ljcos2_parameters... }

However, after the checkpoint is read in by some later simulations, only the first nb_interaction, i.e. the lennard-jones, is set. The lj-cos2 is ignored.

After finding this, I went into the scripts and found such a paragraph in file ESPRESSO/scripts/blockfile_support.tcl

proc blockfile_read_auto_interactions {channel read auto} {

    set data [blockfile $channel read toend]

    foreach d $data { eval "inter $d" }

    return "interactions"

}

Does this mean when the above interactions are read in, ESPResSo actually runs the following line?

inter 1 1 lennard-jones ...some_lj_parameters... lj-cos2 ...some_ljcos2_parameters...

If so, it is apparent why only the first part of lennard-jones interaction is set and why the second part of lj-cos2 is ignored. More importantly, it this explanation happens to be the case, then I guess some revision is necessary on how interactions are stored into and extracted from checkpoint files.

Regards,

Mingyang

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Mingyang Hu

Department of Physics

Carnegie Mellon University