diff --git a/examples/SPIN/gneb/README b/examples/SPIN/gneb/README
index 6f5db6d388..9d43c775b6 100644
--- a/examples/SPIN/gneb/README
+++ b/examples/SPIN/gneb/README
@@ -8,3 +8,6 @@ Run those examples as:
 mpirun -np 3 lmp_mpi -in in.gneb.iron -partition 3x1
 
 You should be able to use any number of replicas >= 3.
+
+In the interpolate/ directory, a c routine is provided to
+interpolate the MEP. 
diff --git a/examples/SPIN/gneb/interpolate/README b/examples/SPIN/gneb/interpolate/README
index d0f75226c5..5cfd267a86 100644
--- a/examples/SPIN/gneb/interpolate/README
+++ b/examples/SPIN/gneb/interpolate/README
@@ -1,7 +1,31 @@
 Interpolate.x tries to perform a cubic polynomial interpolation
-of the MEP found 
+of the MEP.  
 
 Compile the program with:
 gcc interpolate.c -o interpolate.x -lm -lgsl
 
+and then run it as:
+./interpolate.x
 
+Enter N-1 (with N the number of replica).
+The program reads the "neb_init.dat", in which you need to
+replace the current values by your GNEB outputs.
+
+Each line corresponds to a replica, and has to respectively
+contain:
+
+Reac. coords /tab/ pot. energy /tab/ fm dot tangent /tab/
+geodesic dist to next replica
+
+All those information can be provided by the verbose output of
+a neb/spin calculation
+
+The progam outputs the interpolation result, and the
+interpolated MEP in "interpolation_result.dat". 
+
+This code is a courtesy of Aleksei Ivanov, University of
+Iceland.
+For more explanation about this calculation, see Appendix D 
+of the following reference:
+Bessarab, P. F., Uzdin, V. M., & Jónsson, H. (2015). 
+Computer Physics Communications, 196, 335-347. 
diff --git a/examples/SPIN/gneb/interpolate/interpolate.c b/examples/SPIN/gneb/interpolate/interpolate.c
index 48804d53a2..39b1b2e192 100644
--- a/examples/SPIN/gneb/interpolate/interpolate.c
+++ b/examples/SPIN/gneb/interpolate/interpolate.c
@@ -67,8 +67,7 @@ int main() {
   
   // reading input file
 
-  if((data=fopen("reac_coords_iron_verbose.dat","r")) == NULL) {
-  //if((data=fopen("neb_init.dat","r")) == NULL) {
+  if((data=fopen("neb_init.dat","r")) == NULL) {
     printf("Incorrect input file name.");
     return 0;
   }
diff --git a/examples/SPIN/gneb/interpolate/reac_coords_iron_verbose.dat b/examples/SPIN/gneb/interpolate/neb_init.dat
similarity index 100%
rename from examples/SPIN/gneb/interpolate/reac_coords_iron_verbose.dat
rename to examples/SPIN/gneb/interpolate/neb_init.dat