<div style="line-height:1.7;color:#000000;font-size:14px;font-family:arial">Since your system is simple cubic, and your first and second atoms position are (0,0,0) and (-1,0,0), which are both at the vertex position of a cubic, thus the 1st and 2nd atoms at exactly same position (please think about the translation in crystal). Actually, in you input file, atom 1~4 aimed the same position.<br><br><div>--<br>GAO Zhe<br>CMC Lab, Materials Science & Engineering Department,<br>Seoul National University, South Korea<br>        
 </div><div id="divNeteaseMailCard"></div><br>At 2012-03-27 06:33:35,"mohamed makhyoun" <makhyoun2@yahoo.com> wrote:<br> <blockquote id="isReplyContent" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td style="font: inherit;" valign="top">Dear All: <br><br>By running the given input file for pw.x I get the error:<br><br><br>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>     from check_atoms : error #         1<br>     atoms #   1 and #   2 overlap!<br>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>Although I checked the input by XCRYSDEN visualization program and nothing is wrong.<br> I appreciate any help.<br><br>Best Regard<br><br>Mohamed<br>###################################################################<br><br>&CONTROL<br>                 calculation = 'scf' ,<br>                
 prefix='cu3nbs4'<br>                restart_mode = 'from_scratch' ,<br>                  outdir = '$TMP_DIR/' ,<br>                  pseudo_dir = '/home/mohamed/espresso/exec/pseudo' ,<br>                  verbosity = 'default' ,<br><br> /<br> &SYSTEM<br>                           ibrav=1<br>                           celldm(1)= 10.397
 ,<br>                           nat = 20,<br>                        ntyp = 3,<br>                     ecutwfc = 60. ,<br>                     nbnd=90,<br> /<br> &ELECTRONS<br>              conv_thr=1.0D-8 ,<br> /<br>ATOMIC_SPECIES<br>   Nb  92.9064   Nb.pbe-sR-sc-us.UPF<br>   Cu  63.546    Cu.pbe-sR-us.UPF<br>    S   32.06    
 S.pbe-van-bm.UPF<br> ATOMIC_POSITIONS crystal<br>Nb       0.000000000      0.000000000      0.000000000<br>Nb      -1.000000000      0.000000000      0.000000000<br>Nb       0.000000000      0.000000000     -1.000000000<br>Nb       1.000000000      0.000000000      0.000000000<br>Cu       0.500000000      0.000000000      0.000000000<br>Cu       0.000000000      0.000000000     -0.500000000<br>Cu      -0.500000000     
 0.000000000      0.000000000<br>Cu       0.000000000     -0.500000000      0.000000000<br>Cu       0.000000000      0.500000000      0.000000000<br>Cu       0.000000000      0.000000000      0.500000000<br>S        0.242599953      0.242599953      0.242599953<br>S        0.242599953     -0.242599953     -0.242599953<br>S       -0.242599953      0.242599953     -0.242599953<br>S       -0.242599953    
 -0.242599953      0.242599953<br>S       -0.757400047      0.242599953      0.242599953<br>S        0.242599953      0.242599953     -0.757400047<br>S       -0.757400047     -0.242599953     -0.242599953<br>S        0.757400047      0.242599953     -0.242599953<br>S       -0.242599953     -0.242599953     -0.757400047<br>S        0.757400047     -0.242599953      0.242599953<br>K_POINTS gamma<br><br><br></td></tr></tbody></table></blockquote></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></span>