<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
</head>
<body>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear QE users, </div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I hope this email finds you well. </div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I am currently trying to compute the Hubbard U parameters for the Mn[Fe(CN)<sub>6</sub>] material with the HP code. </div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I am following the standard workflow from the HP examples as well as the procedure from the Phys. Chem. Chem. Phys., 2023, 25, 9061-9072 article by Dr Timrov.</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
My procedure is as follows:</div>
<ol start="1" data-editing-info="{"applyListStyleFromLevel":false,"orderedStyleType":1}" style="margin-top: 0px; margin-bottom: 0px; list-style-type: decimal;">
<li style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); margin-top: 0px; margin-bottom: 0px;">
<div role="presentation">vc-relax,</div>
</li><li style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); margin-top: 0px; margin-bottom: 0px;">
<div role="presentation">fake-metal SCF,</div>
</li><li style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); margin-top: 0px; margin-bottom: 0px;">
<div role="presentation">insulator SCF,</div>
</li><li style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); margin-top: 0px; margin-bottom: 0px;">
<div role="presentation">hp.x</div>
</li></ol>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
But then, I get a pair of U values that seem chemically counterintuitive, i.e., chemically I would expect my high-spin Mn(III) to have a larger U value than my low-spin Fe(III). Interestingly, this is not at all what I get from hp.x.</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Please find the inputs and outputs attached. I have omitted the vc-relax output as it is quite a heavy file.</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Please, would you be able to advise on whether I am doing something wrong? </div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
There are also some more theoretical questions relating to the HP code. For example, while I appreciate that the entire DFPT reformulation in terms of monochromatic perturbations allows us to avoid the need for supercells of sizes matching the perturbation
wavelengths, I do not quite understand why the aforementioned paper uses a supercell composed of 8 formula units for LiMn<sub>2</sub>O<sub>4</sub>? Is it generally desirable to use cells with orthogonal lattice vectors with HP?</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Many thanks in advance for your help.</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Best wishes, </div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Krystian</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Krystian A. Gierczak</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);">
PhD Student in the VLD Group,</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);">
Department of Chemistry, University of Oxford</div>
<div style="font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);">
Web: https://deringer.chem.ox.ac.uk</div>
<div style="direction: ltr; font-family: "Helvetica Neue", Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
</body>
</html>