<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div class="msg-body inner undoreset" role="main" style=""><div id="yiv6369728372"><div><div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;"><div id="yiv6369728372"><div><div style="color:#000;background-color:#fff;font-family:times new roman, new york, times, serif;font-size:12pt;"><div>Dear Prof. Blaha</div><div><br></div><div style="color:rgb(0, 0, 0);font-size:16px;font-family:times new roman, new york, times, serif;background-color:transparent;font-style:normal;">I have calculated the optical properties of TiSe2 by MBJ potential with 6000, 50000 and 90000 kpoints which generated after scf by x kgen as discussed in the UG.<br>As discussed in the paper of Prof. Claudia Draxl (computer physics comm. 175, 1-14 (2006)) the sum rule 1 and 2 show 'an effective number of
electrons contributing to the absoption process as a function of energy'.<br>but my calculations lead to :<br>6000 kpoints: <br><pre>sum rule 1: Int(sigma)dw 19.14 <br>sum rule 2: Int(eloss.w)dw 18.93<br>sum rule 3: Int(eloss/w)dw 1.51<br></pre>50000 kpoints<br><pre>sum rule 1: Int(sigma)dw 19.08<br>sum rule 2: Int(eloss.w)dw 18.94<br>sum rule 3: Int(eloss/w)dw 1.52</pre><pre> <br>90000 kpoints<br><br>sum rule 1: Int(sigma)dw 10.125 <br>sum rule 2: Int(eloss.w)dw 10.035<br>sum rule 3: Int(eloss/w)dw 1.51<br></pre>the results show that in 90000 kpoints the value of 'sum rule 2' significantly decreases . in the UG it has mensioned that for the optic we need dense kpoints but how many? how can I check it for optic? <br>Best Regards <br></div><div style="color:rgb(0, 0, 0);font-size:16px;font-family:times new roman, new york, times,
serif;background-color:transparent;font-style:normal;">Ali</div></div></div></div></div></div></div></div></div></body></html>