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    Dear Pooja, <br>
    <br>
    you should first change the line <br>
    <br>
    "CELL_PARAMETERS (angstrom)"<br>
    <br>
    to <br>
    <br>
    "CELL_PARAMETERS (alat)"<br>
    <br>
    <br>
    HTH, <br>
    <br>
    Laurent<br>
    <br>
    <div class="moz-cite-prefix">On 08/01/2020 12:57, Pooja Vyas wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAKPq2FFt9bhp2KGoTFHTXpnHWcFMrD-EjA8gUBBnQqGVHFpEtw@mail.gmail.com">
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        <div>Following is my input file. Since ibrav=0, I removed celldm
          and gave a run, but I face the following error:</div>
        <div> </div>
        <div>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
               task #         0<br>
               from cdiaghg : error #       618<br>
               S matrix not positive definite<br>
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
        </div>
        <div><br>
        </div>
        <div>Input:<br>
        </div>
        <div>&control</div>
            calculation = 'scf',<br>
            prefix = '9.1334'<br>
            tstress= .true.<br>
            tprnfor= .true.<br>
            outdir = '/home/userpooja/cao.oct/'<br>
            pseudo_dir = '/home/userpooja/cao.oct/pseudo/'<br>
         /<br>
         &system<br>
            ibrav =  0,<br>
            celldm(1)=9.1334,<br>
            nat =  64,<br>
            ntyp = 2,<br>
            ecutwfc = 100,<br>
        /<br>
        &electrons<br>
            mixing_beta = 0.7<br>
         <br>
        /<br>
        <br>
        ATOMIC_SPECIES<br>
        <br>
        Ca 40.078  Ca.pbe-nsp-van.UPF<br>
        O 15.999 O.pbe-van_ak.UPF<br>
        <br>
        ATOMIC_POSITIONS (angstrom) <br>
           Ca    2.4165926060    2.4165926060    0.0000000000<br>
           Ca    0.0000000000    0.0000000000    0.0000000000<br>
           Ca    2.4165926060    0.0000000000    2.4165926060<br>
           Ca    0.0000000000    2.4165926060    2.4165926060<br>
            O    4.8331852120    4.8331852120    2.4165926060<br>
            O    2.4165926060    2.4165926060    2.4165926060<br>
            O    4.8331852120    2.4165926060    4.8331852120<br>
            O    2.4165926060    4.8331852120    4.8331852120<br>
           Ca    2.4165926060    2.4165926060    4.8331852120<br>
           Ca    0.0000000000    0.0000000000    4.8331852120<br>
           Ca    2.4165926060    0.0000000000    7.2497778180<br>
           Ca    0.0000000000    2.4165926060    7.2497778180<br>
            O    4.8331852120    4.8331852120    7.2497778180<br>
            O    2.4165926060    2.4165926060    7.2497778180<br>
            O    4.8331852120    2.4165926060    9.6663704240<br>
            O    2.4165926060    4.8331852120    9.6663704240<br>
           Ca    2.4165926060    7.2497778180    0.0000000000<br>
           Ca    0.0000000000    4.8331852120    0.0000000000<br>
           Ca    2.4165926060    4.8331852120    2.4165926060<br>
           Ca    0.0000000000    7.2497778180    2.4165926060<br>
            O    4.8331852120    9.6663704240    2.4165926060<br>
            O    2.4165926060    7.2497778180    2.4165926060<br>
            O    4.8331852120    7.2497778180    4.8331852120<br>
            O    2.4165926060    9.6663704240    4.8331852120<br>
           Ca    2.4165926060    7.2497778180    4.8331852120<br>
           Ca    0.0000000000    4.8331852120    4.8331852120<br>
           Ca    2.4165926060    4.8331852120    7.2497778180<br>
           Ca    0.0000000000    7.2497778180    7.2497778180<br>
            O    4.8331852120    9.6663704240    7.2497778180<br>
            O    2.4165926060    7.2497778180    7.2497778180<br>
            O    4.8331852120    7.2497778180    9.6663704240<br>
            O    2.4165926060    9.6663704240    9.6663704240<br>
           Ca    7.2497778180    2.4165926060    0.0000000000<br>
           Ca    4.8331852120    0.0000000000    0.0000000000<br>
           Ca    7.2497778180    0.0000000000    2.4165926060<br>
           Ca    4.8331852120    2.4165926060    2.4165926060<br>
            O    9.6663704240    4.8331852120    2.4165926060<br>
            O    7.2497778180    2.4165926060    2.4165926060<br>
            O    9.6663704240    2.4165926060    4.8331852120<br>
            O    7.2497778180    4.8331852120    4.8331852120<br>
           Ca    7.2497778180    2.4165926060    4.8331852120<br>
           Ca    4.8331852120    0.0000000000    4.8331852120<br>
           Ca    7.2497778180    0.0000000000    7.2497778180<br>
           Ca    4.8331852120    2.4165926060    7.2497778180<br>
            O    9.6663704240    4.8331852120    7.2497778180<br>
            O    7.2497778180    2.4165926060    7.2497778180<br>
            O    9.6663704240    2.4165926060    9.6663704240<br>
            O    7.2497778180    4.8331852120    9.6663704240<br>
           Ca    7.2497778180    7.2497778180    0.0000000000<br>
           Ca    4.8331852120    4.8331852120    0.0000000000<br>
           Ca    7.2497778180    4.8331852120    2.4165926060<br>
           Ca    4.8331852120    7.2497778180    2.4165926060<br>
            O    9.6663704240    9.6663704240    2.4165926060<br>
            O    7.2497778180    7.2497778180    2.4165926060<br>
            O    9.6663704240    7.2497778180    4.8331852120<br>
            O    7.2497778180    9.6663704240    4.8331852120<br>
           Ca    7.2497778180    7.2497778180    4.8331852120<br>
           Ca    4.8331852120    4.8331852120    4.8331852120<br>
           Ca    7.2497778180    4.8331852120    7.2497778180<br>
           Ca    4.8331852120    7.2497778180    7.2497778180<br>
            O    9.6663704240    9.6663704240    7.2497778180<br>
            O    7.2497778180    7.2497778180    7.2497778180<br>
            O    9.6663704240    7.2497778180    9.6663704240<br>
            O    7.2497778180    9.6663704240    9.6663704240<br>
        <br>
        CELL_PARAMETERS (angstrom)<br>
        2.0 0.0 0.0<br>
        0.0 2.0 0.0<br>
        0.0 0.0 2.0<br>
        <br>
        K_POINTS (automatic)<br>
          11 11 11 1 1 1<br>
        <br>
      </div>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <pre class="moz-quote-pre" wrap="">_______________________________________________
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    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">-- 
                                                       ,,,     __,
                                                      /'^'\   |__|
                                                     ( o o )  |
--------------------------------------------------oOOO--(_)--OO|o------
<a class="moz-txt-link-rfc2396E" href="mailto:Laurent.Pizzagalli@univ-poitiers.fr"><Laurent.Pizzagalli@univ-poitiers.fr></a>
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------------------------------------------    Fax +33 549 49 66 92
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