<div dir="ltr">You can create non equivalent atoms using the w2web interface. You have to use the "split" options to divide the two equivalent positions of Atom 1 into two different atoms. And then label them as 1 and 2 which will make sure that the symmetry operation doesn't realize that you have two equivalent positions. Then you can go on to compute the effective charge for atom 1.<div>
<br></div><div>Alternatively, on your current structure both the atoms are equivalent which means they will have the same effective charge. So, I would suggest that instead of displacing just one atomic positions if you use identical displacement for the both positions, you can compute sum of the effective charges for the two equivalent atoms without any errors. Then you just have to average them.</div>
<div><br></div><div>PS: make sure that you lattice vectors are orthogonal. BerryPI doesn't yet have the capability to compute polarization for non orthogonal case.</div><div><br></div><div>Hope that will help.</div><div>
<br></div><div>Sheikh </div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Oct 13, 2013 at 5:26 AM, Shwetha Gummula <span dir="ltr"><<a href="mailto:shwetha.gummula@gmail.com" target="_blank">shwetha.gummula@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>Dear Wien2k users and developers,<br></div> I want to calculate the
Born effective charges by using the BerryPI code which is in interface
with the wien2k. I have successfully installed and ran the examples. In
order to calculate the Born effective charges of particular atom in particular direction we
have the change the position of that particular element in the
particular direction. But my question is for my compound which is
tetragonal structure (ABO4 type), for particular atom A it created equivalent atoms.<br>
Ex:ATOM -1: X=0.00000000 Y=0.75000000 Z=0.37500000<br> MULT= 2 ISPLIT=-2<br> -1: X=0.00000000 Y=0.25000000 Z=0.62500000<br>A NPT= 781 R0=0.00000500 RMT= 2.1200 Z: <br> if
i change the position of one atom while initializing it is giving error
about the other equivalent position where there position also have to
change. <br>
Ex:ATOM -1: X=0.00000000 Y=0.75000000 Z=0.36500000<br> MULT= 2 ISPLIT=-2<br> -1: X=0.00000000 Y=0.25000000 Z=0.62500000<br>A NPT= 781 R0=0.00000500 RMT= 2.1200 Z: <br><br>In
order to change the position (or perturb) do i have to create the again in w2web page with the perturbed positions (A (0 0.75, 0.365)). What will be the correct procedure. How to create the non equivalent
positions for every element so that we can easily perturb the positions.
please can anyone help me regarding this.<br>
</div>Thanking you</div>
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