<div dir="ltr"><div>Thank you so much for your speedy help, Laurie!</div><div></div><div><br></div><div>I really hope there is no issue here, but when I examined the eigenvalues, I noticed the agreement deteriorates as iteration goes on. In addition, the momentum matrix elements between bands differ a lot. </div><div>Since the first three iterations have no difference, I suspect the mixer could lead to the difference. </div><div>In case.scfm UYTF(J) differs by a minus sign,</div><div></div><div>:INFO Fp Singular value 3.497E+00 Weight 1.0000E+00 Projections -1.728E+02 4.561E+00<br></div><div>:INFO Fp Singular value 3.497E+00 Weight 1.0000E+00 Projections -1.728E+02 -4.561E+00</div><div></div><div>but this may not be the main course. </div><div><br></div><div>Do you have any suggestions where I should check to pin down this disagreement?</div><div><br></div><div>(I have the same compiler version, and the codes are the same. the outputs from both machines are exactly the same for the first three iterations).</div><div><br></div><div>Thanks a lot!</div><div><br></div><div>Guoping</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Fri, Dec 19, 2025 at 12:10 PM Laurence Marks <<a href="mailto:laurence.marks@gmail.com">laurence.marks@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="auto"><div><div>There is no issue. You can multiply U & VT by -1 and the decomposition and the inverse is identical -- see for instance <a href="https://en.wikipedia.org/wiki/Singular_value_decomposition" target="_blank">https://en.wikipedia.org/wiki/Singular_value_decomposition</a> about the non-uniqueness and a stack of more informational. The mixer uses the decomposition for a regularized inverse where this does not matter.</div><div><br></div><div>___<br>Emeritus Professor Laurence Marks (Laurie)<br>Department of Materials Science and Engineering, Northwestern University<br><a href="http://www.numis.northwestern.edu" rel="noreferrer" target="_blank">www.numis.northwestern.edu</a><br>"Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Györgyi</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Dec 19, 2025, 10:35 Guoping Zhang <<a href="mailto:gpzhang.physics@gmail.com" rel="noreferrer" target="_blank">gpzhang.physics@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">Dear Profs. Blaha and Marks and wien users,<br><br>I have a question on how the new Mixer is implemented as it gives me<br>different results on different computers. Different results mean that<br>the eigenvalues differ by 10^-6 ry, so the wavefunctions are even<br>worse. I am using wien2k_13 version, but there is no difference for<br>newer versions.<br><br><br>In FprojmemR1m.F, call DGESVD gets SVD of Vect, but SVD normally<br>produces an arbitrary sign for U and VT for the same Vect like<br>vect 1 1 1.7542057564<br>vect 1 2 1.7522638412<br>vect 2 1 1.7441856025<br>vect 2 2 1.7425017533<br><br>In one case, my U is<br><br><br>debug3c.outputm:MMT91 U VT 1 1 -0.7091042206 -0.7074733729<br>debug3c.outputm:MMT91 U VT 1 2 -0.7051036834 -0.7067399994<br>debug3c.outputm:MMT91 U VT 2 1 -0.7051036834 -0.7067399994<br>debug3c.outputm:MMT91 U VT 2 2 0.7091042206 0.7074733729<br><br>Another case has<br><br>debug11.outputm:MMT91 U VT 1 1 0.7091042206 0.7074733728<br>debug11.outputm:MMT91 U VT 1 2 -0.7051036834 0.7067399994<br>debug11.outputm:MMT91 U VT 2 1 0.7051036834 -0.7067399994<br>debug11.outputm:MMT91 U VT 2 2 0.7091042206 0.7074733728<br><br>I run 4 iterations to activate the mixer. When I diff case.scf, these two<br>cases have no difference to the last digit,<br><br>But after the mixing, it differs a lot though the total energy is the<br>same (which is not my interest).<br><br>My questions are (1) whether the new mixer finally uses some products<br>like (U x VT) to generate the new charge density, and (2) whether you<br>have examples that I use to verify this arbitrary sign does not matter.<br><br>Thank you so much in advance!<br><br>Best wishes,<br><br>Guoping<br><br></div>
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