Dear Heather <br><br>Thanks for your comments. I think that this type of charge (Lowdin) which is nearly the number of valence electrons can not speak about the details of the system.<br>Some electrons are bonding and also, the effect of the core (core electron + nucleus ) is not negligible. I want to compare the real charge of two atoms in my system with each other not their valence electrons. I appreciate your help in advance. <br>
<br>-- <br>Sincerely Yours<br>David G.<br>JCU<br><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Dear David,<br>
<br>
You are right in that the Lowdin charges here refer to the valence electrons<br>
of your system.<br>
<br>
The Lowdin charges are calculated as a sum of the projections of the<br>
extended plane wave valence states onto a pseudo-atomic basis (characterized<br>
by the highest valence s, p, d, f states per your output).<br>
<br>
The numbers are positive and not negative, as you pointed out, because they<br>
refer to the *number* of electrons (i.e. s, p, and so on). In your example,<br>
there appears to be approximately four electrons: 1 s-type and 3 p-type<br>
valence electrons attributed to each atom.<br>
<br>
The code should also a 'spilling parameter' at the bottom of your output<br>
that tells you how well the projections are capturing the description of the<br>
valence states. For instance, the projection is capturing 3.96 electrons<br>
per atom in your example. So, if you expect in your example to have four<br>
valence electrons per atom, then the pseudo-atomic basis is capturing your<br>
extended valence states pretty well.<br>
<br>
Hope that helps!<br>
--<br>
Heather K<br>
Postdoc at Stanford University<br>
<br>
On Fri, Dec 10, 2010 at 5:54 PM, David Grifith <<a href="mailto:david.grifith@gmail.com">david.grifith@gmail.com</a>>wrote:<br>
<br>
> Dear QE Users<br>
><br>
> My calculated "Lowdin Charge" values are "positive" as shown below. I<br>
> thought that they must be the charge of the valence electron ! but the sign<br>
> is positive. Also, I don't know that a pseudopotential package like Quantum<br>
> Espresso considers the "core" charge to be calculated or not ?<br>
><br>
><br>
><br>
> Atom # 1: total charge = 3.9571, s = 0.9145, p = 3.0426, d =<br>
> 0.0000,<br>
> spin up = 1.9786, s = 0.4573, p = 1.5213, d =<br>
> 0.0000,<br>
> spin down = 1.9786, s = 0.4573, p = 1.5213, d =<br>
> 0.0000,<br>
> polarization = 0.0000, s = 0.0000, p = 0.0000, d =<br>
> 0.0000,<br>
> Atom # 2: total charge = 3.9569, s = 0.9154, p = 3.0415, d =<br>
> 0.0000,<br>
> spin up = 1.9785, s = 0.4577, p = 1.5208, d =<br>
> 0.0000,<br>
> spin down = 1.9785, s = 0.4577, p = 1.5208, d =<br>
> 0.0000,<br>
> polarization = 0.0000, s = 0.0000, p = 0.0000, d =<br>
> 0.0000,<br>
> Atom # 3: total charge = 3.9554, s = 0.9153, p = 3.0402, d =<br>
> 0.0000,<br>
> spin up = 1.9777, s = 0.4576, p = 1.5201, d =<br>
> 0.0000,<br>
> spin down = 1.9777, s = 0.4576, p = 1.5201, d =<br>
> 0.0000,<br>
> polarization = 0.0000, s = 0.0000, p = 0.0000, d =<br>
> 0.0000,<br>
> Atom # 4: total charge = 3.9573, s = 0.9164, p = 3.0408, d =<br>
> 0.0000,<br>
> spin up = 1.9786, s = 0.4582, p = 1.5204, d =<br>
> 0.0000,<br>
> spin down = 1.9786, s = 0.4582, p = 1.5204, d =<br>
> 0.0000,<br>
> polarization = 0.0000, s = 0.0000, p = 0.0000, d =<br>
> 0.0000,<br>
> Atom # 5: total charge = 3.9607, s = 0.9155, p = 3.0452, d =<br>
> 0.0000,<br>
> spin up = 1.9804, s = 0.4578, p = 1.5226, d =<br>
> 0.0000,<br>
> spin down = 1.9804, s = 0.4578, p = 1.5226, d =<br>
> 0.0000,<br>
> polarization = -0.0000, s = -0.0000, p = -0.0000, d =<br>
> 0.0000,<br>
> Atom # 6: total charge = 3.9599, s = 0.9146, p = 3.0453, d =<br>
> 0.0000,<br>
> spin up = 1.9800, s = 0.4573, p = 1.5227, d =<br>
> 0.0000,<br>
> spin down = 1.9800, s = 0.4573, p = 1.5227, d =<br>
> 0.0000,<br>
> polarization = -0.0000, s = -0.0000, p = -0.0000, d =<br>
> 0.0000,<br>
> Atom # 7: total charge = 3.9600, s = 0.9148, p = 3.0452, d =<br>
> 0.0000,<br>
> spin up = 1.9800, s = 0.4574, p = 1.5226, d =<br>
> 0.0000,<br>
> spin down = 1.9800, s = 0.4574, p = 1.5226, d =<br>
> 0.0000,<br>
> polarization = -0.0000, s = -0.0000, p = -0.0000, d =<br>
> 0.0000,<br>
><br>
> --<br>
> Sincerely Yours<br>
> David G.<br>
> JCU<br>
><br>
><br>
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