<div dir="ltr"><div dir="ltr">On Sun, Mar 22, 2020 at 5:50 PM Victor Bermudez <<a href="mailto:bermudez@alum.mit.edu">bermudez@alum.mit.edu</a>> wrote:<br></div><div class="gmail_quote"><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
I'm trying to compute the charge density difference for a molecule on a substrate [...] using Postprocessing (pp.x, plot_num=7)</blockquote><div><br></div><div>you should first of all try with the charge density (plot_num=1) and check whether you get sensible numbers<br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> I'm aware that all densities have to be obtained with the same atom positions, ecutwfc, ecutrho, etc., and I've done that.</blockquote><div><br></div><div>and same cell</div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
*** vdW-TS term will be missing in potential *** <br></blockquote><div><br></div><div>as long as you are interested in the charge density, this should be harmless. The initialization of the vdW-TS terms is missing in postprocessing (for some obscure reasons, it crashed)</div><div><br></div><div>Paolo</div><div><br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
(2) The molecule is paramagnetic, so the SCF calculations for n(mol.+slab) and n(mol.) were spin-polarized, but that for n(slab) was not. In obtaining Diff(n) I'm using the highest majority-spin bands for n(mol.+slab) and n(mol.). <br>
Can I then use the highest doubly-occupied band for n(slab) if I set w2/w1 = 0.5 ? <br>
Do I have to do a spin-polarized calculation for n(slab) even though it's diamagnetic ? <br>
Is further adjustment of w2/w1 need to account for the fact that mol.+slab and slab involve a different total number of electrons ? <br>
<br>
(3) The slab comprises a 4x4 supercell with 1 molecule. Should I then set w3/w1 = 1/16 ? Again, is any further adjustment of w3/w1 needed ? <br>
<br>
(4) In the SCF calculations of n(mol.+slab) and n(slab) I used a 3x3 MP grid (because of the large supercell). For n(mol.), on the other hand, I used just the gamma point (because the isolated molecules are far apart).<br>
Is that OK, or should I have used the same MP grid in obtaining n(mol.) ? <br>
<br>
Thanks in advance for your help. <br>
<br>
Best Wishes,<br>
Vic Bermudez<br>
U.S. Naval Research Laboratory (retired) <br>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br><br></div></div></div></div></div></div>