<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Dear Amit, <br><br>Can you please send me your IFC file so I can test it?<br><br>Bests,<br>Eyvaz.<br><br>-------------------------------------------------------------------<br>
Prof. Eyvaz Isaev, <br>
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden <br>
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, <br>
isaev@ifm.liu.se, eyvaz_isaev@yahoo.com<br><br>--- On <b>Mon, 5/24/10, Yamit <i><amit99266@rediffmail.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Yamit <amit99266@rediffmail.com><br>Subject: [Pw_forum] About F_QHA.x<br>To: pw_forum@pwscf.org<br>Date: Monday, May 24, 2010, 5:01 PM<br><br><div id="yiv196565073">Dear All<br>
<br>
I have attempted to calculate the specific heat of Si using "F_QHA.x", and the calculated Silicon phonon dos as an input.<br>
(The calculated Si phonon frequencies are in excellent agreement with available experimental data. )<br>
<br>
As the output of "F_QHA.x", I have obtained the following results, (in QHA.out file)<br>
<br>
############################################################################################################<br>
<br>
# T in K, F_vib in Ry/cell, C_v in R (the universal gas constant by 3N modes), S in k_B<br>
############################################################################################################<br>
# T E_internal F_vibration Specific heat (C_v) Entropy<br>
############################################################################################################<br>
:<br>
:<br>
295.00 0.0139740852 0.0055747646 4.6621714979 4.4956255367<br>
300.00 0.0141222695 0.0054311560 4.6966380876 4.5742737931<br>
305.00 0.0142715257 0.0052850687 4.7298757363 4.6521815403<br>
310.00 0.0144218157 0.0051365259 4.7619351485 4.7293532915<br>
:<br>
:<br>
:<br>
############################################################################################################<br>
<br>
From the above results, at 300 K:<br>
<br>
4.6966380876 * 8.314 = 39.048<br>
(where, Gas constant, R = 8.314 J/(mol K) ) and for Silicon N = 2, so 3N=6 modes<br>
<br>
So, Specific heat, C_v= 38.761 / 3N = 6.5080 J/(mol K)<br>
<br>
Experimentally the Specific heat, C_v of Si at 25 °C (~298) is found equal to 9.789 J·mol−1·K−1. <br>
<br>
Can anybody could explain the reason behind this huge error in the calculation of specific heat ?<br>
<br>
Warm Regards<br>
Amit N. Harode<br>
C R Labs INDIA<br>
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