<html>
<head>
<meta http-equiv='Content-Type' content='text/html; charset=UTF-8'>
</head>
<body>
<style>
font{
line-height: 1.5;
}
</style>
<div style = 'font-family:"微软雅黑"; font-size: 14px; color:#000000; line-height:1.5;'>
<div>
<div>Dear developers,</div><div> I read this tutorial link <a href="http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_disp.html" _src="http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_disp.html">http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_disp.html</a></div><div> It mentioned that if we use ultrasoft pseudopotential, we have to use much higher ecutrho and tighter th2_ph</div><div> I have a few questions:</div><div> 1. What is the reason for a higher ecutrho as well as th2_ph? Any references?</div><div> 2. Do we need a high ecutrho for PAW as well?</div><div> 2. I tried to calc diamond phonon dispersion and use (4 4 4) grid with C.pz-rrkjus.UPF. But I found that the phonon dispersions for ecutrho=150 and ecutrho=450 are exactly the same. Then I don't understand why the tutorial suggest such a high ecutrho as 450? Are there other criterions for a suitable ecutrho that I missed?</div><div> 3. For an arbitrary ultrasoft pseudopotential, how to quickly determine a suitable ecutrho?</div><div><br></div><div>best regards</div><div> </div><div id="ntes-pcmail-signature" style="font-family:'微软雅黑'"><font style="padding: 0; margin:0;"> </font>
</div><br>
</div><style type="text/css">
a#ntes-pcmail-signature-default:hover {
text-decoration: underline;
color: #3593db;
cursor: pointer;
}
</style><!--😀-->
</div>
</body>
</html>