<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Vinicius,<div><br></div><div> it is not clear to me if you want to build the primitive cell of Pt3Sn or a supercell. In the former case you may use a cubic cell (ibrav=1) and put a Sn in the origin and three Pt on the faces of the cube. If you want a supercell, well, it depends if you want to extend the structure along one direction only (hence you should use a tetragonal cell) or isotropically along the three directions (the supercell will still be cubic). I don't see any reason to use ibrav=0 to specify a tetragonal cell as you are doing in your input file. Moreover it is easy to see from your input that atoms 2 and 5 will overlap with the atom in the origin (and with each other) since their positions differ by a vector of Bravais lattice.</div><div><br></div><div> It would be very kind of you if you take a few time to sign your future posts and specify your affiliation. Thanks!</div><div><br></div><div>Regards,</div><div><br></div><div>GS<br><div><br></div><div><div><div>Il giorno 10/ago/2010, alle ore 22.06, Vinícius Bertuzzo Lima ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span id="result_box" class="long_text"><span style="" title="">Greetings!<br></span><span style="background-color: rgb(255, 255, 255);" title="">Before anything, thank you!<br><br></span><span style="background-color: rgb(255, 255, 255);" title="">I'm
trying to optimize a super-cell of Pt-Sn intermetallic, but when I
determine the atomic positions of the crystal, there is overlapping of
atoms, which determine the species as the source. <br></span><span style="background-color: rgb(255, 255, 255);" title=""><br>For
example, if I determine how the platinum atom (0,0,0), the whole basis
of the crystal will, in its vertices of platinum atoms, as my only two
intermetallic is Pt3Sn <br>vertices of the base would be two platinum and
tin.<br><br></span><span style="background-color: rgb(255, 255, 255);" title="">I understand the system, which would by ibrav = 0, but still is not working. </span><span style="background-color: rgb(255, 255, 255);" title="">How would an input on which to determine the position of only two atoms of the base and not the whole basis?<br>
<br></span><span style="background-color: rgb(255, 255, 255);" title="">Down my input:<br><br></span></span><div id=":9o" class="ii gt"><div id=":9p"><div><b>&CONTROL</b></div><div><b> calculation = 'vc-relax' ,</b></div>
<div><b> restart_mode = 'from_scratch' ,</b></div><div><b> outdir = '/home/vinicius/tmp' ,</b></div>
<div><b> pseudo_dir = '/home/vinicius/espresso-4.1.</b><b>3/pseudo' ,</b></div><div><b> /</b></div><div><b> &SYSTEM</b></div><div><b> ibrav = 0,</b></div><div><b> celldm(1) = 7.10082033,</b></div>
<div><b> nat = 5,</b></div><div><b> ntyp = 2,</b></div><div><b> ecutwfc = 30 ,</b></div><div><b> ecutrho = 300 ,</b></div><div><b> occupations = 'smearing' ,</b></div>
<div><b> degauss = 0.05 ,</b></div><div><b> smearing = 'methfessel-paxton' ,</b></div><div><b> /</b></div><div><b> &ELECTRONS</b></div><div><b> conv_thr = 1.D-8 ,</b></div>
<div><b> mixing_beta = 0.7D0 ,</b></div>
<div><b> /</b></div><div><b> &IONS</b></div><div><b> ion_dynamics = 'bfgs' ,</b></div><div><b> bfgs_ndim = 3 ,</b></div><div><b> /</b></div><div><b> &CELL</b></div><div><b> cell_dynamics = 'bfgs' ,</b></div>
<div><b> cell_dofree = 'xyz' ,</b></div><div><b> /</b></div><div><b>CELL_PARAMETERS cubic </b></div><div><b> 0.000000000 0.000000000 4.200000000 </b></div><div><b> 0.000000000 1.000000000 0.000000000 </b></div>
<div><b>
1.000000000 0.000000000 0.000000000 </b></div><div><b>ATOMIC_SPECIES</b></div><div><b> Pt 195.08400 Pt.pw91-n-van.UPF </b></div><div><b> Sn 118.71070 Sn.pw91-n-van.UPF </b></div><div><b>ATOMIC_POSITIONS alat </b></div>
<div><b> Pt 0.000000000 0.000000000 0.000000000 0 0 0 </b></div>
<div><b> Sn 1.000000000 0.000000000 0.000000000 0 0 0 </b></div><div><b> Pt 0.500000000 0.500000000 0.707100000 0 0 0 </b></div><div><b> Pt 0.500000000 0.500000000 -0.707100000 0 0 0 </b></div>
<div><b> Sn 0.000000000 1.000000000 0.000000000 </b></div><div><b>K_POINTS automatic </b></div><div><b> 4 4 1 0 0 0 </b><br></div>
</div></div><span id="result_box" class="long_text"><span style="background-color: rgb(255, 255, 255);" title=""><br></span><span style="background-color: rgb(255, 255, 255);" title="">Thanks again. </span><span style="" title="">And have a great day!</span></span>
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<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><span class="Apple-style-span" style="color: rgb(126, 126, 126); font-size: 16px; font-style: italic; "><br class="Apple-interchange-newline">§ Gabriele Sclauzero, EPFL SB ITP CSEA</span></div><div><font class="Apple-style-span" color="#7E7E7E"><i> PH H2 462, Station 3, CH-1015 Lausanne</i></font></div></span>
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