No subject

>

>
4.6966380876  * 8.314 = 39.048
>
(where, Gas constant, R = 8.314 J/(mol K) ) and for Silicon N = 2, so 3N=6 modes
>

>
So, Specific heat, C_v= 38.761 / 3N = 6.5080  J/(mol K)
>

>
Experimentally the Specific heat, C_v of Si at 25 °C (~298) is found equal to 9.789 J·mol−1·K−1. 
>

>
Can anybody could explain the reason behind this huge error in the calculation of specific heat ?
>

>
Warm Regards
>
Amit N. Harode
>
C R Labs INDIA
>


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--=_376bbf633a2cfff03e99b121171615e6
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html; charset="UTF-8"

<br />
Dear Prof Nicola Marzari<br />
<br />
Thank you for your reply! The phonon values from this work are in good agre=
ement (with error of ~1-2 %) with the values reported in Giannozzi, PRB 43-=
7231-1991.<br />
<br />
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D<br />
Table : (Frequency in cm^{-1},)<br />
<br />
- & Current work & PRB 43-7231-1991 <br />
<br />
Gamma_{TO/LO} & 525.350461 & 517 <br />
<br />
L_{TA} & 109 & 111 <br />
L_{LA} & 379 & 378 <br />
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D<br />
<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 mode=
s), 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 />