Doesn't move correctly.

private Animator playerAnimator;
private float moveHorizontal;
private float moveVertical;
private Vector3 movement;
private float turningSpeed = 20f;
private Rigidbody playerRigidbody;

// Use this for initialization
void Start () {
    playerAnimator = GetComponent<Animator>();

    playerRigidbody = GetComponent<Rigidbody>();
}

// Update is called once per frame
void Update () {
    moveHorizontal = Input.GetAxisRaw("Horizontal");
    moveVertical = Input.GetAxisRaw("Vertical");

    movement = new Vector3(moveHorizontal, 0.0f, moveVertical);
}

void FixedUpdate (){
    if (movement != Vector3.zero) {


        Quaternion targetRotation = Quaternion.LookRotation(movement, Vector3.up);

        Quaternion newRotation = Quaternion.Lerp (playerRigidbody.rotation, targetRotation, turningSpeed * Time.deltaTime);

        playerRigidbody.MoveRotation(newRotation);

        playerAnimator.SetFloat("Speed", 3f);
    }else {
        playerAnimator.SetFloat("Speed", 0f);
    }
}