<div style="line-height:1.7;color:#000000;font-size:14px;font-family:arial">According to your input information, nat=48, I think you wanted to make 2x2x2 rutile-TiO2 supercell with a substitutional Nb. However, you setted celldm(1) and ATOMIC_POSITIONS wrong.<br>You may set celldm(1)=1 and keep CELL_PARAMETERS; or keep celldm(1)=8.7 and set CELL_PARAMETERS as<br>2.000   0.000   0.000<br>0.000   2.000   0.000<br>0.000   0.000   1.288<br>For ATOMIC_POSITIONS, you may set it as:<br>ATOMIC_POSITIONS {crystal}<br>  O   0.1523998693948630   0.1523998693948630   0.0000000000000000<br>  O   0.3476001306051368   0.3476001306051368   0.0000000000000000<br>  O   0.0976001306051369   0.4023998693948629   0.2500000000000001<br>  O   0.4023998693948629   0.0976001306051369   0.2500000000000001<br>  O   0.6523998693948631   0.1523998693948630   0.0000000000000000<br>  O   0.8476001306051368   0.3476001306051368   0.0000000000000000<br>  O   0.5976001306051370   0.4023998693948629   0.2500000000000001<br>  O   0.9023998693948629   0.0976001306051369   0.2500000000000001<br>  O   0.1523998693948630   0.6523998693948631   0.0000000000000000<br>  O   0.3476001306051368   0.8476001306051368   0.0000000000000000<br>  O   0.0976001306051369   0.9023998693948629   0.2500000000000001<br>  O   0.4023998693948629   0.5976001306051370   0.2500000000000001<br>  O   0.6523998693948631   0.6523998693948631   0.0000000000000000<br>  O   0.8476001306051368   0.8476001306051368   0.0000000000000000<br>  O   0.5976001306051370   0.9023998693948629   0.2500000000000001<br>  O   0.9023998693948629   0.5976001306051370   0.2500000000000001<br>  O   0.1523998693948630   0.1523998693948630   0.5000000000000000<br>  O   0.3476001306051368   0.3476001306051368   0.5000000000000000<br>  O   0.0976001306051369   0.4023998693948629   0.7500000000000001<br>  O   0.4023998693948629   0.0976001306051369   0.7500000000000001<br>  O   0.6523998693948631   0.1523998693948630   0.5000000000000000<br>  O   0.8476001306051368   0.3476001306051368   0.5000000000000000<br>  O   0.5976001306051370   0.4023998693948629   0.7500000000000001<br>  O   0.9023998693948629   0.0976001306051369   0.7500000000000001<br>  O   0.1523998693948630   0.6523998693948631   0.5000000000000000<br>  O   0.3476001306051368   0.8476001306051368   0.5000000000000000<br>  O   0.0976001306051369   0.9023998693948629   0.7500000000000001<br>  O   0.4023998693948629   0.5976001306051370   0.7500000000000001<br>  O   0.6523998693948631   0.6523998693948631   0.5000000000000000<br>  O   0.8476001306051368   0.8476001306051368   0.5000000000000000<br>  O   0.5976001306051370   0.9023998693948629   0.7500000000000001<br>  O   0.9023998693948629   0.5976001306051370   0.7500000000000001<br> Ti  -0.0000000000000000  -0.0000000000000000   0.0000000000000000<br> Ti   0.2499999999999998   0.2499999999999998   0.2500000000000001<br> Ti   0.5000000000000000  -0.0000000000000000   0.0000000000000000<br> Ti   0.7499999999999998   0.2499999999999998   0.2500000000000001<br> Ti  -0.0000000000000000   0.5000000000000000   0.0000000000000000<br> Ti   0.2499999999999998   0.7499999999999998   0.2500000000000001<br> Ti   0.5000000000000000   0.5000000000000000   0.0000000000000000<br> Ti   0.7499999999999998   0.7499999999999998   0.2500000000000001<br> Ti  -0.0000000000000000  -0.0000000000000000   0.5000000000000000<br> Ti   0.2499999999999998   0.2499999999999998   0.7500000000000001<br> Ti   0.5000000000000000  -0.0000000000000000   0.5000000000000000<br> Ti   0.7499999999999998   0.2499999999999998   0.7500000000000001<br> Ti  -0.0000000000000000   0.5000000000000000   0.5000000000000000<br> Ti   0.2499999999999998   0.7499999999999998   0.7500000000000001<br> Ti   0.5000000000000000   0.5000000000000000   0.5000000000000000<br> Ti   0.7499999999999998   0.7499999999999998   0.7500000000000001<br><div>--<br>GAO Zhe<br>CMC Lab, MSE, SNU, Seoul, S.Korea<br>        
</div><div id="divNeteaseMailCard"></div><br>At 2011-09-07 20:22:30,"Winfred Mulwa" <mulwawinfred@yahoo.com> wrote:<br> <blockquote id="isReplyContent" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Dear all</span></div><div><br><span></span></div><div><span>       I have tried doing a vc-relax on the attached TiO2 rutile supercell,</span></div><div><span>the calculations stop after a few minutes without giving any error. <br></span></div><div><span>What might be the problem?<br></span></div></div></blockquote></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></span>