diff --git a/input/in.lj b/input/in.lj
index 20198eb..eb8c76e 100644
--- a/input/in.lj
+++ b/input/in.lj
@@ -23,4 +23,4 @@ thermo 10
 
 dump dmpvtk all vtk 10 dump%_*.vtu
 
-run		100
+run		30
diff --git a/src/inputCL.cpp b/src/inputCL.cpp
index df96366..9f0bf50 100644
--- a/src/inputCL.cpp
+++ b/src/inputCL.cpp
@@ -48,6 +48,7 @@
 
 #include <Cabana_Core.hpp>
 
+#include <cstdlib>
 #include <inputCL.h>
 #include <output.h>
 #include <types.h>
@@ -116,8 +117,12 @@ void InputCL::read_args( int argc, char *argv[] )
                  "                                (N = positive integer)\n",
                  "                                (PATH = location of ",
                  "directory)\n" );
-            log( std::cout, "  --sparse : "
-                            "create a vacuum for an unbalanced system\n" );
+            log( std::cout,
+                 "  --vacuum [N]:             Create a vacuum for "
+                 "an unbalanced system, enlarging the simulation "
+                 "box N times\n"
+                 "                                (N = floating-point "
+                 "multiplier, must be bigger than 1.0)\n" );
         }
 
         // Read Lammps input deck
@@ -235,9 +240,14 @@ void InputCL::read_args( int argc, char *argv[] )
             i += 3;
         }
 
-        else if ( ( strcmp( argv[i], "--sparse" ) == 0 ) )
+        else if ( ( strcmp( argv[i], "--vacuum" ) == 0 ) )
         {
-            sparse = true;
+            vacuum = true;
+            vacuum_rate = std::atof( argv[i + 1] );
+            if ( vacuum_rate < 1.0 )
+                log_err( std::cout,
+                         "Vacuum rate smaller than 1.0 not allowed." );
+            i += 2;
         }
 
         else if ( ( strstr( argv[i], "--kokkos-" ) == NULL ) )
diff --git a/src/inputCL.h b/src/inputCL.h
index 15a2c64..b161bf0 100644
--- a/src/inputCL.h
+++ b/src/inputCL.h
@@ -63,7 +63,8 @@ class InputCL
     int layout_type;
     int nnp_layout_type;
     int device_type;
-    bool sparse = false;
+    bool vacuum = false;
+    double vacuum_rate = 1.0;
 
     int dumpbinary_rate, correctness_rate;
     bool dumpbinaryflag, correctnessflag;
diff --git a/src/inputFile_impl.h b/src/inputFile_impl.h
index 9213a71..4023615 100644
--- a/src/inputFile_impl.h
+++ b/src/inputFile_impl.h
@@ -512,12 +512,12 @@ void InputFile<t_System>::create_lattice( Comm<t_System> *comm )
     T_X_FLOAT max_z = lattice_constant * lattice_nz;
     std::array<T_X_FLOAT, 3> global_low = { 0.0, 0.0, 0.0 };
     std::array<T_X_FLOAT, 3> global_high = { max_x, max_y, max_z };
-    if ( commandline.sparse )
+    if ( commandline.vacuum )
     {
         // Create a vacuum for an unbalanced system.
-        global_high[0] *= 2;
-        global_high[1] *= 2;
-        global_high[2] *= 2;
+        global_high[0] *= commandline.vacuum_rate;
+        global_high[1] *= commandline.vacuum_rate;
+        global_high[2] *= commandline.vacuum_rate;
     }
     system->create_domain( global_low, global_high, comm_ghost_cutoff );
     s = *system;