--- trunk/src/math/Quaternion.hpp	2009/11/25 20:02:06	1390
+++ trunk/src/math/Quaternion.hpp	2012/03/10 16:00:24	1687
@@ -36,7 +36,8 @@
  * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).             
  * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).          
  * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 24107 (2008).          
- * [4]  Vardeman & Gezelter, in progress (2009).                        
+ * [4]  Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010).
+ * [5]  Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
  */
  
 /**
@@ -254,7 +255,7 @@ namespace OpenMD{
        return rotation angle from -PI to PI 
     */
     inline Real get_rotation_angle() const{
-      if( w < (Real)0.0 )
+      if( w() < (Real)0.0 )
         return 2.0*atan2(-sqrt( x()*x() + y()*y() + z()*z() ), -w() );
       else
         return 2.0*atan2( sqrt( x()*x() + y()*y() + z()*z() ),  w() );
@@ -312,15 +313,15 @@ namespace OpenMD{
                                c.z());
 
       this->normalize();    // if "from" or "to" not unit, normalize quat
-      w += 1.0f;            // reducing angle to halfangle
-      if( w <= 1e-6 ) {     // angle close to PI
+      w() += 1.0f;            // reducing angle to halfangle
+      if( w() <= 1e-6 ) {     // angle close to PI
         if( ( from.z()*from.z() ) > ( from.x()*from.x() ) ) {
-          this->data_[0] =  w;    
+          this->data_[0] =  w();    
           this->data_[1] =  0.0;       //cross(from , Vector3d(1,0,0))
           this->data_[2] =  from.z();
           this->data_[3] = -from.y();
         } else {
-          this->data_[0] =  w;
+          this->data_[0] =  w();
           this->data_[1] =  from.y();  //cross(from, Vector3d(0,0,1))
           this->data_[2] = -from.x();
           this->data_[3] =  0.0;