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        <div><br></div><div dir="ltr" data-setdir="false">Thank you Stefano, <br><br>now it is very clear.  <br><br>Carlos</div>
        
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                    En lunes, 29 de julio de 2019 16:44:23 CEST, Stefano de Gironcoli <degironc@sissa.it> escribió:
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    <p><tt>g_psi multiplies the correction vector by an approximation of
        the inverse of (H-eS), typically just the inverse of the
        diagonal .</tt></p>
    <p><tt>regterg is the real version of the routine: that is
        appropriate the one for k==Gamma</tt></p>
    <p><tt>in this case psi is real in real space which means that the
        Fourier components at G and -G are complex conjugate of each
        other.</tt></p>
    <p><tt>the normalization is as usual <br clear="none">
      </tt></p>
    <p><tt>1 = \sum_G psi(G)^* psi(G)   when summing over all G <br clear="none">
      </tt></p>
    <p><tt>but only half of them (the "positive" G) are stored and the
        normalization is computed as</tt></p>
    <p><tt>1 = psi(0)* psi(0) + 2.0 \sum_G/=0 psi(G)* psi(G)   or rather<br clear="none">
      </tt></p>
    <p><tt>1 = 2.0 \sum_G psi(G)* psi(G)   -  psi(0)* psi(0)</tt></p>
    <p><tt>the processor with gstart==2 is the one for which the first
        component is G=0<br clear="none">
      </tt></p>
    <p><tt>HTH</tt></p>
    <p><tt>stefano<br clear="none">
      </tt></p>
    <div class="yiv0464603218yqt7977757139" id="yiv0464603218yqt26978"><div class="yiv0464603218moz-cite-prefix">On 29/07/19 15:59, carlossiero siero
      wrote:<br clear="none">
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        <div dir="ltr">Dear Users, <br clear="none">
          <br clear="none">
          I have been digging in the regterg.f90 subroutine and I was
          wondering if somebody could tell me what the calling to g_psi
          (line 286) is doing?<br clear="none">
          <br clear="none">
          <span>                |     CALL g_psi( npwx, npw, notcnv, 1,
            psi(1,nb1), ew(nb1) )</span> <br clear="none">
          <br clear="none">
          I thought the correction vectors, |psi> = (<span>H - e*S)
            |psi>,</span> were already stored in psi, so there is no
          need to do any inversion or anything else. <br clear="none">
          <br clear="none">
          Also, running a 1processor calculation, the normalization goes
          through line 299:<br clear="none">
           <br clear="none">
          <span>                |      IF ( gstart == 2 ) ew(n) = ew(n)
            - psi(1,nbn) * psi(1,nbn)<br clear="none">
          </span><br clear="none">
          What is the purpose of substrating the psi product of the
          first element on each of the new vectors?<br clear="none">
          <br clear="none">
          Thanks so much for your help! <br clear="none">
          <br clear="none">
          Carlos </div>
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