Response to referee's comments.

We would like to thank the referees for their helpful comments.
Enclosed is our very slightly revised manuscript, following the
suggestions of the referees.  The changes and comments are as
follows.

First referee -- "minor" suggestion:  We have added a few
sentences to the abstract to better describe our results.

Second referee --

1.  We have added the values of the computational parameters used
to section III of the manuscript.

2.  The k-point sampling convergence was checked by doing the
optical calculations for CdWO$_4$ with 54 inequivalent k-points.  The
results were nearly identical to the results for 63 inequivalent
k-points.   A comment to about this was added to the manuscript.
We believe that the reason that we can use a relatively small
number of k-points for these materials is that the unit cell is
rather large and the band dispersions are rather small.

3. The reason that we report the DOS using a Gaussian smearing formula is
to avoid the interpolation spikes of the tetrahedron method,
making it easier to compare peak heights. A brief phase about this
has been added to the manuscript.

4.  We corrected these typo's.  Thanks for pointing them out.