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<div><span style="font-family:Helvetica; font-size:12px">Dear Eduardo,</span><br style="font-family:Helvetica; font-size:12px">
<br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">ESM is one of a variant of a slab calculation. So, you need to put an appropriate thickness of vacuum for a slab calculation. As you</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">know,
the criterion of the minimum thickness of vacuum is sufficiently thick enough to avoid the overlap between the wave function</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">(or charge density)
from both sides of the slab.</span><br style="font-family:Helvetica; font-size:12px">
<br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">If the thickness is 16AA in your model, then you can use this value as the total thickness of the vacuum region in ESM calculation.</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">So
you need to put 8AA thickness vacuum on both sides of the slab. The length of the unit cell along z-direction is (8 + slab</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">thickness + 8)
AA.</span><span style="font-family:Helvetica; font-size:12px"> </span><br style="font-family:Helvetica; font-size:12px">
<br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">More precisely, we need to put a sufficiently thick vacuum on both sides to ensure that the wave function (or charge density)</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">decays
to zero at the cell edge (z=L/2).</span><br style="font-family:Helvetica; font-size:12px">
<br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">Best regards,</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">Minoru</span><br style="font-family:Helvetica; font-size:12px">
<br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">--------------------------------------------------------------------------------------------------------</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">Minoru Otani</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">National Institute of Advanced Industrial Science and Technology</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">Research Centre for Computational Design of Advanced Functional Materials</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">email :</span><span style="font-family:Helvetica; font-size:12px"> </span><span style="font-family:Helvetica; font-size:12px">minoru.otani@aist.go.jp</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">tel : +81-29-861-5202</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">fax : +81-29-861-3171</span><br style="font-family:Helvetica; font-size:12px">
<span style="font-family:Helvetica; font-size:12px">---------------------------------------------------------------------------------------------------------</span>
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<div>On Jul 24, 2017, at 23:36, Eduardo Menendez <eariel99@gmail.com> wrote:</div>
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<div class="">I think the answer to how to create vacuum is in the example ESM_example.<br class="">
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Let me present a related question. How much can we reduce the width of vacuum in the unit cell when using esm_bc='bc1'?
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<div class="">Eduardo Menendez Proupin<br class="">
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