diff --git a/src/atom_vec.cpp b/src/atom_vec.cpp
index 78903d6a7f..eec09cf58a 100644
--- a/src/atom_vec.cpp
+++ b/src/atom_vec.cpp
@@ -2470,7 +2470,7 @@ int AtomVec::process_fields(char *str, const char *default_str, Method *method)
   // allocate memory in method
   method->resize(nfield);
 
-  int *index = method->index;
+  std::vector<int> & index = method->index;
   int match;
 
   for (int i = 0; i < nfield; i++) {
@@ -2523,40 +2523,12 @@ void AtomVec::init_method(int nfield, Method *method)
    Method class members
 ------------------------------------------------------------------------- */
 
-AtomVec::Method::~Method()
-{
-  delete [] pdata;
-  delete [] datatype;
-  delete [] cols;
-  delete [] maxcols;
-  delete [] collength;
-  delete [] plength;
-  delete [] index;
-}
-
 void AtomVec::Method::resize(int nfield) {
-  delete [] pdata;
-  delete [] datatype;
-  delete [] cols;
-  delete [] maxcols;
-  delete [] collength;
-  delete [] plength;
-  delete [] index;
-  pdata = nullptr;
-  datatype = nullptr;
-  cols = nullptr;
-  maxcols = nullptr;
-  collength = nullptr;
-  plength = nullptr;
-  index = nullptr;
-
-  if (nfield > 0) {
-    pdata = new void*[nfield];
-    datatype = new int[nfield];
-    cols = new int[nfield];
-    maxcols = new int*[nfield];
-    collength = new int[nfield];
-    plength = new void*[nfield];
-    index = new int[nfield];
-  }
+  pdata.resize(nfield);
+  datatype.resize(nfield);
+  cols.resize(nfield);
+  maxcols.resize(nfield);
+  collength.resize(nfield);
+  plength.resize(nfield);
+  index.resize(nfield);
 }
diff --git a/src/atom_vec.h b/src/atom_vec.h
index d1915ba508..a8f5f5ec22 100644
--- a/src/atom_vec.h
+++ b/src/atom_vec.h
@@ -191,16 +191,14 @@ class AtomVec : protected Pointers {
   const char *default_create,*default_data_atom,*default_data_vel;
 
   struct Method {
-    void **pdata = nullptr;
-    int *datatype = nullptr;
-    int *cols = nullptr;
-    int **maxcols = nullptr;
-    int *collength = nullptr;
-    void **plength = nullptr;
-    int *index = nullptr;
+    std::vector<void *> pdata;
+    std::vector<int> datatype;
+    std::vector<int> cols;
+    std::vector<int*> maxcols;
+    std::vector<int> collength;
+    std::vector<void *> plength;
+    std::vector<int> index;
 
-    Method() = default;
-    ~Method();
     void resize(int nfield);
   };