No subject

<br />
4.6966380876 * 8.314 =3D 39.048<br />
(where, Gas constant, R =3D 8.314 J/(mol K) ) and for Silicon N =3D 2, so 3=
N=3D6 modes<br />
<br />
So, Specific heat, C_v=3D 38.761 / 3N =3D 6.5080 J/(mol K)<br />
<br />
Experimentally the Specific heat, C_v of Si at 25 =C2=B0C (~298) is found e=
qual to 9.789 J=C2=B7mol=E2=88=921=C2=B7K=E2=88=921.<br />
<br />
Can anybody could explain the reason behind this huge error in the calculat=
ion of specific heat ?<br />
Regards<br />
Amit N.Harode<br />
CR Labs INDIA<br />
<br />
<br />
> Try to compare your calculated phonons and phonon DOS for Si first - > do=
 they<br />
> come out as obtained e.g. by Giannozzi/De Gironcoli/Pavone/Baroni > PRB 1=
991 ?<br />
<br />
> nicola<br />
On Mon, 24 May 2010 18:38:31 +0530  wrote<br />
>Dear All<br />
><br />
<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 />
><br />
(The calculated Si phonon frequencies are in excellent agreement with avail=
able experimental data. )<br />
><br />
<br />
><br />
As the output of "F_QHA.x", I have obtained the following results, (in QHA.=
out file)<br />
><br />
<br />
><br />
###########################################################################=
#################################<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 />
###########################################################################=
#################################<br />
><br />
#   T         E_internal        F_vibration          Specific heat (C_v)   =
    Entropy<br />
><br />
###########################################################################=
#################################<br />
><br />
:<br />
><br />
:<br />
><br />
  295.00      0.0139740852      0.0055747646           4.6621714979        =
  4.4956255367<br />
><br />
 300.00      0.0141222695      0.0054311560           4.6966380876         =
 4.5742737931<br />
><br />
 305.00      0.0142715257      0.0052850687           4.7298757363         =
 4.6521815403<br />
><br />
 310.00      0.0144218157      0.0051365259           4.7619351485         =
 4.7293532915<br />
><br />
:<br />
><br />
:<br />
><br />
:<br />
><br />
###########################################################################=
#################################<br />
><br />
<br />
><br />