[Re:02] How to decide ewidth, edelt, and bzqlty

Posted on : April 21, 2017 (Fri) 20:28:16

by Administrator

Dear Ikeda,

The smaller the delta, the larger the number of k-points needed. The advantage of using a smaller delta is that can retain the finer structure of the band (delta corresponds to the inverse life time of the states or the energy resolution). However, using small delta obviously requires large number k-points to obtain the overall structure of energy bands. As Hitoshi wrote, delta=0.001 would be a good choice in most cases. On the other hand ewidth is not a parameter that controls the accuracy or convergence. It is a quantity that must be set properly: in some cases 0.7Ry would be fine but another case may requires as large as 2Ry.

Best regards,

KKR Administrators