code: public static final double angle(Atom a, Atom b){
  
  		Vector3d va = new Vector3d(a.getCoordsAsPoint3d());
  		Vector3d vb = new Vector3d(b.getCoordsAsPoint3d());
  
  		return Math.toDegrees(va.angle(vb));
  
  	}
docs: Gets the angle between two vectors
  
  @param a
  an Atom object
  @param b
  an Atom object
  @return Angle between a and b in degrees, in range [0,180]. If either
  vector has length 0 then angle is not defined and NaN is returned