No subject

Tue May 11 17:31:48 CEST 2010

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 Â°C (~298) is found equal to 9.789 JÂ·molâˆ’1Â·Kâˆ’1.

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

Regards

Amit N.Harode

CR Labs INDIA

> Try to compare your calculated phonons and phonon DOS for Si first - > do they

> come out as obtained e.g. by Giannozzi/De Gironcoli/Pavone/Baroni > PRB 1991 ?

> nicola

On Mon, 24 May 2010 18:38:31 +0530ï¿½ wrote

>Dear All

>

>

I have attempted to calculate the specific heat of Si using "F_QHA.x", and the calculated Silicon phonon dosï¿½ as an input.

>

(The calculated Si phonon frequencies are in excellent agreement with available experimental data. )

>

>

As the output of "F_QHA.x", I have obtained the following results, (in QHA.out file)

>

>

############################################################################################################

>

>

# T in K, F_vib in Ry/cell, C_v in R (the universal gas constant by 3N modes), S in k_B

>

############################################################################################################

>

#ï¿½ ï¿½ï¿½ Tï¿½ ï¿½ ï¿½ ï¿½ ï¿½ï¿½ E_internalï¿½ ï¿½ ï¿½ ï¿½ F_vibrationï¿½ ï¿½ ï¿½ ï¿½ ï¿½ Specific heat (C_v)ï¿½ ï¿½ ï¿½ ï¿½ï¿½ Entropy

>

############################################################################################################

>

:

>

:

>

ï¿½ 295.00ï¿½ ï¿½ ï¿½ 0.0139740852ï¿½ ï¿½ ï¿½ 0.0055747646ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ï¿½ 4.6621714979ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ 4.4956255367

>

 300.00ï¿½ ï¿½ ï¿½ 0.0141222695ï¿½ ï¿½ ï¿½ 0.0054311560ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ï¿½ 4.6966380876ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ 4.5742737931

>

 305.00ï¿½ ï¿½ ï¿½ 0.0142715257ï¿½ ï¿½ ï¿½ 0.0052850687ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ï¿½ 4.7298757363ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ 4.6521815403

>

 310.00ï¿½ ï¿½ ï¿½ 0.0144218157ï¿½ ï¿½ ï¿½ 0.0051365259ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ï¿½ 4.7619351485ï¿½ ï¿½ ï¿½ ï¿½ ï¿½ 4.7293532915

>

:

>

:

>

:

>

############################################################################################################

>

>