--- /home/sjplimp/oldpizza/src/pair.py	2005-09-14 10:09:22.000000000 -0600
+++ /home/sjplimp/pizza/src/pair.py	2005-09-14 10:07:58.000000000 -0600
@@ -104,7 +104,7 @@
       self.lj4.append(ntypes * [0])
       for j in xrange(ntypes):
         epsilon_ij = sqrt(epsilon[i]*epsilon[j])
-        sigma_ij = 0.5 * (sigma[i] + sigma[j])
+        sigma_ij = sqrt(sigma[i]*sigma[j])
         self.lj3[i][j] = 4.0 * epsilon_ij * pow(sigma_ij,12.0);
         self.lj4[i][j] = 4.0 * epsilon_ij * pow(sigma_ij,6.0);
   
@@ -148,7 +148,7 @@
       self.lj4.append(ntypes * [0])
       for j in xrange(ntypes):
         epsilon_ij = sqrt(epsilon[i]*epsilon[j])
-        sigma_ij = 0.5 * (sigma[i] + sigma[j])
+        sigma_ij = sqrt(sigma[i]*sigma[j])
         self.lj3[i][j] = 4.0 * epsilon_ij * pow(sigma_ij,12.0);
         self.lj4[i][j] = 4.0 * epsilon_ij * pow(sigma_ij,6.0);