<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:DengXian;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:DengXian;
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
text-align:justify;
text-justify:inter-ideograph;
font-size:10.5pt;
font-family:DengXian;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
span.EmailStyle21
{mso-style-type:personal-compose;
font-family:DengXian;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link="#0563C1" vlink="#954F72" style='word-wrap:break-word;text-justify-trim:punctuation'><div class=WordSection1><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Dear QE-Users,<br><br>I am doing CPMD with cp.x for iron oxide system following the official tutorial which introduced two steps (Step1: Reaching the electronic ground state; Step 2: Relax the system) before doing cpmd.<br><br>However, in both the electronic minimization and ionic minimization processes, I found that the force cannot converge (forc_conv_thr=1.0D-3 cannot be satisfied), while it is relative easy for electronic energy and total energy to converge (ekin_conv_thr=1.0D-6, etot_conv_thr= 1.0D-4). <br><br>I am wondering whether this is caused by that the initial crystal structure is not fully relaxed with the current pseudopotential. Is it necessary to do "vc-relax" with pw.x before doing CPMD with cp.x ? If yes, which parameters should be kept to be the same in both pw.x and cp.x?<br><br>Any comment or suggestion will be much appreciated.<br><br>Thanks,<br>Kejiang</span><b><span lang=EN-US style='font-size:11.0pt'><br><br></span></b><span lang=EN-US>-------------------------------------------------<br></span><span lang=EN-US style='font-size:9.0pt'>Dr. Kejiang Li<br>School of Metallurgical and Ecological Engineering,<br>University of Science and Technology Beijing<br>Xueyuan Rd., Haidian District, Beijing 100083, P. R. China</span><span lang=EN-US style='font-size:7.5pt'><br><a href="https://kejiangli.com/" target="_blank">https://kejiangli.com/</a></span><span lang=EN-US style='font-size:9.0pt'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>