From b33974cd198365c08e34395122f1c484ed133126 Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Tue, 14 Jul 2020 12:44:50 -0400
Subject: [PATCH] add code to check for duplicate atom IDs in Bodies section

---
 src/atom.cpp | 11 +++++++++++
 src/atom.h   |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/src/atom.cpp b/src/atom.cpp
index a0e9791e21..0ebb7c73a9 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -217,6 +217,8 @@ Atom::Atom(LAMMPS *lmp) : Pointers(lmp)
   map_bucket = NULL;
   map_hash = NULL;
 
+  unique_tags = nullptr;
+
   atom_style = NULL;
   avec = NULL;
 
@@ -295,6 +297,8 @@ Atom::~Atom()
   // delete mapping data structures
 
   map_delete();
+
+  delete unique_tags;
 }
 
 /* ----------------------------------------------------------------------
@@ -1554,6 +1558,8 @@ void Atom::data_bodies(int n, char *buf, AtomVec *avec_body, tagint id_offset)
   int *ivalues = NULL;
   double *dvalues = NULL;
 
+  if (!unique_tags) unique_tags = new std::set<tagint>;
+
   // loop over lines of body data
   // if I own atom tag, tokenize lines into ivalues/dvalues, call data_body()
   // else skip values
@@ -1565,6 +1571,11 @@ void Atom::data_bodies(int n, char *buf, AtomVec *avec_body, tagint id_offset)
     if (tagdata <= 0 || tagdata > map_tag_max)
       error->one(FLERR,"Invalid atom ID in Bodies section of data file");
 
+    if (unique_tags->find(tagdata) == unique_tags->end())
+      unique_tags->insert(tagdata);
+    else
+      error->one(FLERR,"Duplicate atom ID in Bodies section of data file");
+
     ninteger = force->inumeric(FLERR,strtok(NULL," \t\n\r\f"));
     ndouble = force->inumeric(FLERR,strtok(NULL," \t\n\r\f"));
 
diff --git a/src/atom.h b/src/atom.h
index 0b0bbfc8ad..4dac15d758 100644
--- a/src/atom.h
+++ b/src/atom.h
@@ -16,6 +16,7 @@
 
 #include "pointers.h"
 #include <map>
+#include <set>
 #include <string>
 
 namespace LAMMPS_NS {
@@ -241,6 +242,7 @@ class Atom : protected Pointers {
   int map_user;                   // user requested map style:
                                   // 0 = no request, 1=array, 2=hash, 3=yes
   tagint map_tag_max;             // max atom ID that map() is setup for
+  std::set<tagint> *unique_tags;  // set to ensure that bodies have unique tags
 
   // spatial sorting of atoms