Merge pull request #285 from akohlmey/fix-ipi-update

[Syntax:]

fix ID group-ID ipi address port \[unix\] :pre

fix ID group-ID ipi address port \[unix\] \[reset\] :pre

ID, group-ID are documented in "fix"_fix.html command

ipi = style name of this fix command

address = internet address (FQDN or IP), or UNIX socket name

port = port number (ignored for UNIX sockets)

optional keyword = {unix}, if present uses a unix socket :ul

optional keyword = {unix}, if present uses a unix socket

optional keyword = {reset}, if present reset electrostatics at each call :ul

[Examples:]

fix 1 all ipi my.server.com 12345

fix 1 all ipi mysocket 666 unix

fix 1 all ipi mysocket 666 unix reset

[Description:]

initial configuration is ignored, as it will be substituted with the

coordinates received from i-PI before forces are ever evaluated.

A note of caution when using potentials that contain long-range 

electrostatics, or that contain parameters that depend on box size:

all of these options will be initialized based on the cell size in the

LAMMPS-side initial configuration and kept constant during the run. 

This is required to e.g. obtain reproducible and conserved forces. 

If the cell varies too wildly, it may be advisable to reinitialize 

these interactions at each call. This behavior can be requested by 

setting the {reset} switch. 

[Restart, fix_modify, output, run start/stop, minimize info:]

There is no restart information associated with this fix, since all

#include "compute.h"

#include "comm.h"

#include "neighbor.h"

#include "irregular.h"

#include "domain.h"

#include "compute_pressure.h"

#include <errno.h>

/* ---------------------------------------------------------------------- */

FixIPI::FixIPI(LAMMPS *lmp, int narg, char **arg) :

  Fix(lmp, narg, arg)

  Fix(lmp, narg, arg), irregular(NULL)

{

  /* format for fix:

   *  fix  num  group_id ipi host port [unix]

  inet   = ((narg > 5) && (strcmp(arg[5],"unix") == 0) ) ? 0 : 1;

  master = (comm->me==0) ? 1 : 0;

  // check if forces should be reinitialized and set flag

  reset_flag = ((narg > 6 && (strcmp(arg[5],"reset") == 0 )) || ((narg > 5) && (strcmp(arg[5],"reset") == 0)) ) ? 1 : 0;

  hasdata = bsize = 0;

  // creates a temperature compute for all atoms

  newarg[4] = (char *) "virial";

  modify->add_compute(5,newarg);

  delete [] newarg;

  // create instance of Irregular class

  irregular = new Irregular(lmp);

}

/* ---------------------------------------------------------------------- */

  free(host);

  modify->delete_compute("IPI_TEMP");

  modify->delete_compute("IPI_PRESS");

  delete irregular;

}

  domain->xz = cellh[2]*posconv;

  domain->yz = cellh[5]*posconv;

  // signal that the box has (or may have) changed

  // do error checks on simulation box and set small for triclinic boxes

  domain->set_initial_box();

  // reset global and local box using the new box dimensions

  domain->reset_box();

  // signal that the box has (or may have) changed

  domain->box_change = 1;

  if (kspace_flag) force->kspace->setup();

  // picks local atoms from the buffer

  double **x = atom->x;

    }

  }

  // insure atoms are in current box & update box via shrink-wrap

  // has to be be done before invoking Irregular::migrate_atoms()

  //   since it requires atoms be inside simulation box

  if (domain->triclinic) domain->x2lamda(atom->nlocal);

  domain->pbc();

  domain->reset_box();

  if (domain->triclinic) domain->lamda2x(atom->nlocal);

  // move atoms to new processors via irregular()

  // only needed if migrate_check() says an atom moves to far

  if (domain->triclinic) domain->x2lamda(atom->nlocal);

  if (irregular->migrate_check()) irregular->migrate_atoms();

  if (domain->triclinic) domain->lamda2x(atom->nlocal);

  // check if kspace solver is used

  if (reset_flag && kspace_flag) {

    // reset kspace, pair, angles, ... b/c simulation box might have changed.

    //   kspace->setup() is in some cases not enough since, e.g., g_ewald needs

    //   to be reestimated due to changes in box dimensions.

    force->init();

    // setup_grid() is necessary for pppm since init() is not calling

    //   setup() nor setup_grid() upon calling init().

    if (force->kspace->pppmflag) force->kspace->setup_grid();

    // other kspace styles might need too another setup()?

  } else if (!reset_flag && kspace_flag) {

    // original version

    force->kspace->setup();

  }

  // compute PE. makes sure that it will be evaluated at next step

  modify->compute[modify->find_compute("thermo_pe")]->invoked_scalar = -1;

  modify->addstep_compute_all(update->ntimestep+1);

  char *host; int port; int inet, master, hasdata;

  int ipisock, me; double *buffer; long bsize;

  int kspace_flag;

  int reset_flag;

 private:

  class Irregular *irregular;

};

}