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<div class="">Dear Akmal,</div>
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<div class="">Lorenzo is right: forces and stresses with LDA+U on orthogonalized wave functions require an extra (non trivial) implementation in the code to compute the derivative of the overlap matrix (between atomic wfc’s of different atoms) with respect
to atomic positions and strains, and incorporates it in the expression of the corresponding derivative of the (orthogonalized) atomic wfc.</div>
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<div class="">Of course you can do a structural relaxation with ‘atomic’ wave functions and total energy calculations on the resulting structure with ‘oath-atomic’. This is of course not strictly consistent. However, for the states for which the use of Hubbard
correction is most justified (the localized d or f states), due to their localized nature, the overlap matrix should be small, and there should not be very large difference between the two approaches. So the contributions to forces and stress coming from the
overlap matrix should be relatively small.</div>
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<div class="">This is of course not a general rule but something that needs to be checked case by case. For example you could compute some of the forces on Hubbard atoms by a finite difference approach with ortho-atomic and compare them with those the code
computes with ‘atomic” projections.</div>
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<div class="">Hope this helps,</div>
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<div class="">Matteo</div>
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<blockquote type="cite" class="">
<div class="">On Nov 13, 2017, at 10:45 AM, Akmal Khan <<a href="mailto:khanakmal982@gmail.com" class="">khanakmal982@gmail.com</a>> wrote:</div>
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<div dir="ltr" class="">Thank You..<br class="">
Is it necessary to use this parameter during relaxation..What if this is used later in scf calculation when forces and stress are already implented during relaxation..?<br class="">
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<div class="gmail_extra"><br class="">
<div class="gmail_quote">On Mon, Nov 13, 2017 at 2:03 PM, Lorenzo Paulatto <span dir="ltr" class="">
<<a href="mailto:paulatz@gmail.com" target="_blank" class="">paulatz@gmail.com</a>></span> wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="auto" class="">
<div class="">
<div dir="auto" class="">Dear Akmal, you have three alternatives :</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">1. Implement them yourself </div>
<div dir="auto" class="">2. Offer a sufficient incentive for someone else to implement them for you</div>
<div dir="auto" class="">3. Pay a student or postdoc to implement them for you (result may vary) </div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">Kind regards <br class="">
<br class="">
<div data-smartmail="gmail_signature" dir="auto" class="">-- <br class="">
Lorenzo Paulatto<br class="">
Written on a virtual keyboard with real fingers</div>
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<div class="gmail_extra"><br class="">
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<div class="">
<div class="h5">On 13 Nov 2017 9:56 a.m., "Akmal Khan" <<a href="mailto:khanakmal982@gmail.com" target="_blank" class="">khanakmal982@gmail.com</a>> wrote:<br type="attribution" class="">
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<blockquote class="m_8988271451314094563quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div class="">Dear QE users and experts,<br class="">
the orthogonalization of the atomic wave functions is controlled from input through the parameter U_projection_type equal to “ortho-atomic”. But then forces and stress are not implemented during relaxation in LDA+U calculation.How can we orthogonalize
wave function and implement forces and stress at the same time.?<br class="">
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Thank You,<br class="">
</div>
A.Khan<br class="">
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M.phil Research Student<br class="">
</div>
Hazara University Pakistan. <br class="">
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************************************************</div>
<div class="">Matteo Cococcioni</div>
<div class="">Theory and Simulation of Materials</div>
<div class="">École Polytechnique Fédérale de Lausanne</div>
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