--- trunk/src/restraints/ObjectRestraint.cpp	2014/09/22 19:18:35	2020
+++ trunk/src/restraints/ObjectRestraint.cpp	2014/10/16 19:13:51	2024
@@ -70,6 +70,8 @@ namespace OpenMD {
       
       RotMat3x3d temp = A * refA_.transpose();
 
+      Vector3d euler = temp.toEulerAngles();
+
       Quat4d quat = temp.toQuaternion();
 
       RealType twistAngle;
@@ -78,13 +80,16 @@ namespace OpenMD {
       
       quat.toSwingTwist(swingX, swingY, twistAngle);
 
+
       RealType p;
       Vector3d tTwist, tSwing;
 
       if (restType_ & rtTwist){
-        RealType dTwist = twistAngle - twist0_;
-        RealType dVdtwist = kTwist_ * sin(dTwist);
-        p = kTwist_ * (1.0 - cos(dTwist) );
+        RealType dTwist = twistAngle - twist0_;      
+        /// RealType dVdtwist = kTwist_ * sin(dTwist);
+        /// p = kTwist_ * (1.0 - cos(dTwist) );
+        RealType dVdtwist = kTwist_ * dTwist;
+        p = 0.5 * kTwist_ * dTwist * dTwist;
         pot_ += p;
         tBody -= dVdtwist * V3Z;
         if (printRest_) restInfo_[rtTwist] = std::make_pair(twistAngle, p);
@@ -92,8 +97,10 @@ namespace OpenMD {
 
       if (restType_ & rtSwingX){
         RealType dSwingX = swingX - swingX0_;
-        RealType dVdswingX = kSwingX_ * 0.5 * sin(2.0 * dSwingX);
-        p = 0.25 * kSwingX_ * (1.0 - cos(2.0 * dSwingX));
+        /// RealType dVdswingX = kSwingX_ * 0.5 * sin(2.0 * dSwingX);
+        /// p = 0.25 * kSwingX_ * (1.0 - cos(2.0 * dSwingX));
+        RealType dVdswingX = kSwingX_ * dSwingX;        
+        p = 0.5 * kSwingX_ * dSwingX * dSwingX;
         pot_ += p;
         tBody -= dVdswingX * V3X;
         if (printRest_) restInfo_[rtSwingX] = std::make_pair(swingX, p);
@@ -101,8 +108,10 @@ namespace OpenMD {
 
       if (restType_ & rtSwingY){
         RealType dSwingY = swingY - swingY0_;
-        RealType dVdswingY = kSwingY_ * 0.5 * sin(2.0 * dSwingY);
-        p = 0.25 * kSwingY_ * (1.0 - cos(2.0 * dSwingY));
+        /// RealType dVdswingY = kSwingY_ * 0.5 * sin(2.0 * dSwingY);
+        /// p = 0.25 * kSwingY_ * (1.0 - cos(2.0 * dSwingY));
+        RealType dVdswingY = kSwingY_ * dSwingY;        
+        p = 0.5 * kSwingX_ * dSwingY * dSwingY;
         pot_ += p;
         tBody -= dVdswingY * V3Y;
         if (printRest_) restInfo_[rtSwingY] = std::make_pair(swingY, p);