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Dear Suza:<div><br class="webkit-block-placeholder"></div><div>I am not sure I understand clearly your question, but it seems to me that an isolated infinite and charged layer cannot have any well defined work function, because it would generate a uniform electric field in the vacuum, with a corresponding potential energy that diverges linearly far from the layer. The lack of convergence of any quantities related to the electrostatic potential energy in the vacuum (such as the work function) is exactly what I would expect. Let alone the extra complications arising from periodic boundary conditions ...</div><div><br class="webkit-block-placeholder"></div><div>Cheers - Stefano Baroni</div><div><br class="webkit-block-placeholder"></div><div><br class="webkit-block-placeholder"></div><div><div><div>On Sep 7, 2007, at 6:50 PM, Suza W wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><br> <br> Dear all,<br> <br> I'm running the scf calculation for a single charged<br> layer. I find that the chemical potential is very sensitive <br> with the vacuum length. It does not get<br> converged even after using a large vacuum of 100 a. u.<br> What should one do to get a converged value?<br> <br> Yours sincerely, <br> Suza <br> Raman Research Institute<br> <br> <br><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Pw_forum mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://www.democritos.it/mailman/listinfo/pw_forum">http://www.democritos.it/mailman/listinfo/pw_forum</a></div> </blockquote></div><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; 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