<div> </div>
<div>about why i use etot_conv_thr<br>as well as force_conv_thr= 1.d-6 Ry</div>
<div>as usual,in vasp and castep software,about 1.d-4 ev is ok</div>
<div>why it is so different between these DFT software ?</div>
<div>i don not understand.</div>
<div>need your help</div>
<div><br><br> </div>
<div><span class="gmail_quote">2007/7/13, Stefano de Gironcoli <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:degironc@sissa.it" target="_blank">degironc@sissa.it</a>>:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">a tipical bond stiffness, if I recall correctly, is in the range of 0.1-1.0<br>Ry/bohr^2 thus a threshold of
1.d-6 Ry/bohr in the force means that you are<br>asking a numerical accuracy in your interatomic distances of the order of<br>1.d-5-1.d-6 bohr... are you sure you really need it ?<br>best regards,<br>stefano deGironcoli, SISSA & DEMOCRITOS
<br><br>Quoting xu yuehua <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:njuxuyuehua@gmail.com" target="_blank">njuxuyuehua@gmail.com</a>>:<br><br>> hello all<br>> i am doing relax.<br>
> in my inputfile,<br>> i use Bohr> and the output is<br>> atom 1 type 1 force = 0.00000290 0.00000095 -0.00000364<br>> atom 2 type 1 force = 0.00000081 -0.00000108 0.00000033
<br>> atom 3 type 1 force = -0.00000435 -0.00000425 -0.00000160<br>> atom 4 type 1 force = - 0.00000312 -0.00000321 -0.00000080<br>> atom 5 type 1 force = -0.00000446
-0.00000036 -0.00000273<br>> atom 6 type 1 force = -0.00000048 0.00000230 0.00000112<br>> atom 7 type 1 force = 0.00000164 0.00000118 0.00000060<br>> atom 8 type 1 force =
0.00000131 -0.00000040 0.00000145<br>> atom 9 type 2 force = -0.00000362 0.00000154 -0.00000201<br>> atom 10 type 2 force = - 0.00000029 0.00000191 0.00000302<br>> atom 11 type 2 force =
0.00000576 -0.00000134 0.00000194<br>> atom 12 type 2 force = 0.00000390 0.00000276 0.00000233<br>><br>> Total force = 0.000015 Total SCF correction = 0.000054<br>> SCF correction compared to forces is too large, reduce conv_thr
<br>><br>> The maximum number of steps has been reached.<br>> my qustion is ,force at every atom is ok ,but why the program asks to <br>> reduce conv_thr<br>> my conv_thr is not enough small ?<br>> or my total relax step (50) is not adequate?
<br>> is there any principle about these parameter?<br>> need your help<br>> thanks a lot<br>> --<br>> Xu Yuehua<br>> physics Department of Nanjing university<br>> China<br>><br><br><br><br><br>----------------------------------------------------------------
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<br clear="all"><br>-- <br>Xu Yuehua<br>physics Department of Nanjing university <br>China