} else {
Vector3f vectorBA = new Vector3f();
Vector3f vectorBC = new Vector3f();
float radians = Measure.computeAngle(getAtom(1), getAtom(2), getAtom(3), vectorBA, vectorBC, false);
Vector3f vectorAxis = new Vector3f();
vectorAxis.cross(vectorBA, vectorBC);
aa = new AxisAngle4f(vectorAxis.x, vectorAxis.y, vectorAxis.z, radians);
vectorBA.normalize();
vectorBA.scale(0.5f);
pointArc = new Point3f(vectorBA);