diff -Naur lammps-26Mar08/src/pair_yukawa.cpp lammps-27Mar08/src/pair_yukawa.cpp
--- lammps-26Mar08/src/pair_yukawa.cpp	2008-01-02 12:24:46.000000000 -0700
+++ lammps-27Mar08/src/pair_yukawa.cpp	2008-03-27 16:56:35.000000000 -0600
@@ -217,6 +217,7 @@
     offset[i][j] = a[i][j] * screening / cut[i][j];
   } else offset[i][j] = 0.0;
 
+  a[j][i] = a[i][j];
   offset[j][i] = offset[i][j];
 
   return cut[i][j];