From 87a5a35bad564f50e9fbf7d04c7529c79e55e4c0 Mon Sep 17 00:00:00 2001
From: Michele Ceriotti <michele.ceriotti@gmail.com>
Date: Sun, 20 Nov 2016 00:44:23 +0100
Subject: [PATCH] A tiny bugfix for the reset flag, and a brief explanation of
the changes
---
doc/src/fix_ipi.txt | 16 +++++++++++++---
src/USER-MISC/fix_ipi.cpp | 2 +-
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/doc/src/fix_ipi.txt b/doc/src/fix_ipi.txt
index 3899f50529..b1533830bc 100644
--- a/doc/src/fix_ipi.txt
+++ b/doc/src/fix_ipi.txt
@@ -10,18 +10,19 @@ fix ipi command :h3
[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:]
@@ -57,6 +58,15 @@ input are listed in the same order as in the data file of LAMMPS. The
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
diff --git a/src/USER-MISC/fix_ipi.cpp b/src/USER-MISC/fix_ipi.cpp
index 20b3c90f8a..67c9cc8ee2 100644
--- a/src/USER-MISC/fix_ipi.cpp
+++ b/src/USER-MISC/fix_ipi.cpp
@@ -195,7 +195,7 @@ FixIPI::FixIPI(LAMMPS *lmp, int narg, char **arg) :
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) ) ? 1 : 0;
+ reset_flag = ((narg > 6 && (strcmp(arg[5],"reset") == 0 )) || ((narg > 5) && (strcmp(arg[5],"reset") == 0)) ) ? 1 : 0;
hasdata = bsize = 0;
--
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