--- trunk/OOPSE/libmdtools/BondExtensions.cpp	2003/03/21 17:42:12	378
+++ trunk/OOPSE/libmdtools/BondExtensions.cpp	2003/06/24 19:57:54	564
@@ -12,3 +12,25 @@ ConstrainedBond::ConstrainedBond( Atom &a, Atom &b, do
 }
 
 
+HarmonicBond::HarmonicBond(Atom &a, Atom &b, double theR0, double theK0 ){
+  
+  set_atoms( a, b );
+  d0 = theR0;
+  k0 = theK0;
+  c_potential_E = 0.0;
+}
+
+
+double HarmonicBond::bond_force( double r_ab ){
+
+  double force;
+  double dr, dr2;
+
+  dr = r_ab - d0;
+  dr2 = dr * dr;
+
+  c_potential_E = k0 * dr2;
+  force = -2.0 * k0 * dr;
+  return force;
+ 
+}