<div dir="ltr">Dear Paolo,<div>Thank you, this is what Lorenzo Paulatto suggested, too:</div><div><span style="color:rgb(80,0,80)">the dynmat.x (not matdyn.x) code computes the IR cross section, if you</span><br style="color:rgb(80,0,80)"><span style="color:rgb(80,0,80)">give it in input the dynamical matrix at Gamma with effective charges.</span><br style="color:rgb(80,0,80)"><span style="color:rgb(80,0,80)">In recent versions of the code, the calculation is done in</span><br style="color:rgb(80,0,80)"><span style="color:rgb(80,0,80)">LR_Modules/dynmat_sub.f90, subroutine RamanIR, and it is quite</span><br style="color:rgb(80,0,80)"><span style="color:rgb(80,0,80)">straightforward. At a certain point the IR cross section is computed as</span><br style="color:rgb(80,0,80)"><br style="color:rgb(80,0,80)"><span style="color:rgb(80,0,80)"> infrared(nu) = 2.d0*(polar(1)**2+polar(2)**2+</span><span style="color:rgb(80,0,80)">polar(3)**2)*irfac</span> </div><div> <br></div><div>So, replacing this by:</div><div><span style="color:rgb(80,0,80)">infrared(nu) = 2.d0*(</span><span style="color:rgb(80,0,80)">polar(3)**2)*irfac</span> <br></div><div>should do what I want (only the Z component of induced dipole is IR active). I'll do some tests soon...</div><div><br></div><div>Best regards,</div><div>Michal</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 8 Jan 2021 at 11:43, 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>The dipole induced by a phonon can be computed from phonon displacements and effective charges: see variable "polar", computed in routine RamanIR, file LR_Modules/dynmat_sub.f90, called by PHonon/PH/dynmat.f90</div><div><br></div><div>Paolo<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jan 7, 2021 at 10:58 PM Michal Krompiec <<a href="mailto:michal.krompiec@gmail.com" target="_blank">michal.krompiec@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">Hello,<br><div><br></div><div>In Reflection-Absorption IR (IR at grazing incidence), only modes that induce a nonzero dipole in the direction normal to the surface contribute to the spectrum. Is it possible to simulate this in QE? </div><div>In other words: how do I calculate the IR spectrum of flexural phonons of a 2D system?</div><div><br></div><div>Best regards,</div><div><br></div><div>Michal Krompiec, Merck KGaA</div></div>
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Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu" rel="noreferrer" target="_blank">www.max-centre.eu</a>)<br>
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