<div dir="ltr">Thanks Paolo,<div><br></div><div>I understand now where the sinus comes from.</div><div><br></div><div>Elena</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 8 Sept 2021 at 08:46, Paolo Giannozzi <<a href="mailto:p.giannozzi@gmail.com">p.giannozzi@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>What we want to compute is V(\vec q) = (1/\Omega) \int V(r) e^{i\vec q \cdot \vec r}dr^3.
V(r) contains an atomic part plus a term Ze^2 erf(r)/r removing the long-range term
and is a function of |\vec r| only. The integral can be written in radial coordinates and integrated wrt \theta and \phi. FInally: V(q) = 4\pi/\Omega \int V(r) (sin(qr)/qr)r^2 dr =
4\pi/\Omega \int (r V(r)) (sin(qr)/q) dr.</div><div><br></div><div>Paolo<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Sep 7, 2021 at 5:15 PM Elena Cannuccia <<a href="mailto:elena.cannuccia@univ-amu.fr" target="_blank">elena.cannuccia@univ-amu.fr</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Dear all,<div><br></div><div>I am interested in understanding the calculation of pseudopotential in plane waves. I have started from the subroutine vloc_of_g.f90.</div><div><br></div><div>I am aware of the fact that a separation of the short and long range part of the Coulomb potential is obtained by means of the error function, and the subsequent treatment of the two parts in order to get the Fourier transform of the Coulomb potential.</div><div><br></div><div>I do not understand the multiplication by r(ir) at line 103</div><div>aux1 (ir) =r (ir) * vloc_at (ir) + zp * e2 * erf (r (ir))<br></div><div>and why, a few lines below, the Fourier transform is obtained by </div><div>sin (gx * r (ir) ) / gx . Is it because the function to be transformed is odd?</div><div><br></div><div>Some references will be really appreciated.</div><div>Thank you very much</div><div><br></div><div>Elena Cannuccia</div><div>Aix Marseille Université <br></div><div><br></div><div><br><div><br></div><div><br></div></div></div>
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