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<div>What happens if you consider the crystal as SC, rather than FCC?</div></div></blockquote>
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<div>The gap is direct when the crystal is considered as SC. The bottom of conduction band and the top of valence band are both at Gamma.</div>
<div>The first Brillouin zone of the FCC is larger than that of the SC. The reduction of the brillouin zone of the SC crystal may induce the K point near X in FCC superpose with Gamma in SC, so the gap of SC is direct . </div>
<div>Am I right?</div>
<div> </div></div><br>-- <br>Y. C. Cheng<br>Department of Phyics<br>Nanjing University<br>Nanjing 210093<br>P. R. China<br>Tel: 86-25-83592907<br>Email: <a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:yccheng.nju@gmail.com" target="_blank">yccheng.nju@gmail.com</a>