> > 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 > _______________________________________________ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum --=_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 />
