diff --git a/segmentmodel.py b/segmentmodel.py
index 8f3dd57b8b592e5dc16ab2b9351665fc955c6912..9018fc4e0830a42cc22d84c930252b9d3007cef8 100644
--- a/segmentmodel.py
+++ b/segmentmodel.py
@@ -1656,14 +1656,14 @@ class SegmentModel(ArbdModel):
 
             conversion = 0.014393265 # units "pN/AA" kcal_mol/AA^2
             if b1.type_.name[0] == "D" and b2.type_.name[0] == "D":
-                elastic_modulus = 1000 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
+                elastic_modulus_times_area = 1000 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
                 d = 3.4*sep
-                k = conversion*elastic_modulus/d
+                k = conversion*elastic_modulus_times_area/d
             else:
                 ## TODO: get better numbers our ssDNA model
-                elastic_modulus = 800 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
+                elastic_modulus_times_area = 800 # pN http://markolab.bmbcb.northwestern.edu/marko/Cocco.CRP.02.pdf
                 d = 5*sep
-                k = conversion*elastic_modulus/d
+                k = conversion*elastic_modulus_times_area/d
                 # print(sep,d,k)
               
             if b1 not in dists: