Unity 3D Torque Based LookAt

using UnityEngine;
using System.Collections;

public class TorqueLookAt : MonoBehaviour {

        public Transform target;
        public float force = 0.1f;


        // Update is called once per frame
        void Update () {

                Vector3 targetDelta = target.position - transform.position;

                //get the angle between transform.forward and target delta
                float angleDiff = Vector3.Angle(transform.forward, targetDelta);

                // get its cross product, which is the axis of rotation to
                // get from one vector to the other
                Vector3 cross = Vector3.Cross(transform.forward, targetDelta);

                // apply torque along that axis according to the magnitude of the angle.
                rigidbody.AddTorque(cross * angleDiff * force);


        }
}