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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>
</tt></p>
<p><tt>1 = \sum_G psi(G)^* psi(G) when summing over all G <br>
</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>
</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>
</tt></p>
<p><tt>HTH</tt></p>
<p><tt>stefano<br>
</tt></p>
<div class="moz-cite-prefix">On 29/07/19 15:59, carlossiero siero
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:740511965.2641336.1564408790050@mail.yahoo.com">
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<div dir="ltr" data-setdir="false">Dear Users, <br>
<br>
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>
<br>
<span> | CALL g_psi( npwx, npw, notcnv, 1,
psi(1,nb1), ew(nb1) )</span> <br>
<br>
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>
<br>
Also, running a 1processor calculation, the normalization goes
through line 299:<br>
<br>
<span> | IF ( gstart == 2 ) ew(n) = ew(n)
- psi(1,nbn) * psi(1,nbn)<br>
</span><br>
What is the purpose of substrating the psi product of the
first element on each of the new vectors?<br>
<br>
Thanks so much for your help! <br>
<br>
Carlos </div>
</div>
<br>
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