<p>Hi Zaid,</p>
<p> </p>
<p>I realised I had made a small mistake in the reply. <span style="color: #008000;">The plasmon is defined as where<strong> ε1</strong> (i.e. the real part) crosses zero</span> <span style="color: #008000;">with a positive slope</span> and NOT ε2. ε2 goes to zero at very high energy values when no valence or semi-core shell excitation is possible. On the contrary ε1 fluctuates between postive and negative values.</p>
<p> </p>
<p>Sorry about the mistake.</p>
<p> </p>
<p>All the best.</p>
<p>Kulpreet</p>
<p>On Fri, 12 Apr 2013 15:41:10 +0800, Zaid <raheskoon@gmail.com> wrote:</p>
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<div>Respected Kulpreet<br /><br /></div>
I appreciate the way you explained my question. Thank you for suggesting books.<br />Thank you so much.<br /><br /></div>
Best Regard's</div>
M. Zain</div>
<div class="gmail_extra"><br /><br />
<div class="gmail_quote">On Fri, Apr 12, 2013 at 3:17 PM, Kulpreet Virdi <span><<a href="mailto:kulpreet.virdi@cup.uni-muenchen.de">kulpreet.virdi@cup.uni-muenchen.de</a>></span> wrote:<br />
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<p>Hi Zaid,</p>
<p> </p>
<p>yes, one way of identifying the Plasmon (energy) is the maximum in loss function (electron energy loss plot) however this is not always correct. The loss function is given by Im [-1/ε] which is equal to [ε2/(ε1^2+ε2^2)]. In the loss function you would see a maximum when there is a local minimum of (ε1^2+ε2^2) or a local maximum of ε2.</p>
<p> </p>
<p>The local maxima of ε2 imply interband transition(s) ; which are often visible in loss spectrum especially for materials containing transition or heavy metals. However a minima of (ε1^2+ε2^2) implies a plasmon excitation.</p>
<p> </p>
<p><span style="color: #ff0000;">T</span><span style="color: #ff0000;">he most often used definition of plasmon is when ε2 crosses zero</span> [and a minmum of ε1^2+ε2^2 ] with a positive slope with respect to the energy axis. For details you can check either of these</p>
<p> </p>
<p>M. Fox, Optical Properties of Solids (Oxford University Press,<br />Oxford, UK, 2010).</p>
<p> </p>
<p>V. Gallegos-Orozco, R. Martınez-Sanchez, and F. Espinosa-<br />Magana, Phys. Rev. B 77, 045128 (2008).</p>
<p> </p>
<p>V. J. Keast, A. J. Scott, M. J. Kappers, C. T. Foxon, and C. J.<br />Humphreys, Phys. Rev. B 66, 125319 (2002).</p>
<p> </p>
<p>I guess someone else could help you with the effective number of electrons.</p>
<p> </p>
<p>All the best,</p>
<p> </p>
<p>Kulpreet</p>
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<p>On Fri, 12 Apr 2013 12:30:09 +0800, Zaid <<a href="mailto:raheskoon@gmail.com">raheskoon@gmail.com</a>> wrote:</p>
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<div>Respected Wien Users<br /><br /></div>
I am inexperience in calculating optical properties May any one guide me how to calculate Plasmon energy and Number of effective electrons ? After some effort I came to know that the energy associated to highest peak value in Electron loss plot will be Plasmon energy. While value for No of effective electrons can be obtained from X KRAM sumrule. Can Any one confirm this information true ? And which sum rule should be selected ? <br /><br /></div>
<div>Best Regards</div>
M, Zaid</div>
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