<br /> <br /> <br /> <br /> <br /> <br /> <br /> 4.6966380876 * 8.314 =3D 39.048<br /> <br /> <br /> <br /> (where, Gas constant, R =3D 8.314 J/(mol K) ) and for Silicon N =3D 2, so 3= N=3D6 modes<br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> So, Specific heat, C_v=3D 38.761 / 3N =3D 6.5080 J/(mol K)<br /> <br /> <br /> <br /> <br /> <br /> <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 /> <br /> <br /> <br /> <br /> <br /> <br /> Can anybody could explain the reason behind this huge error in the calculat= ion of specific heat ?<br /> <br /> <br /> <br /> Regards<br /> <br /> <br /> <br /> Amit N.Harode<br /> <br /> <br /> <br /> CR Labs INDIA<br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> > Try to compare your calculated phonons and phonon DOS for Si first - > do= they<br /> <br /> <br /> <br /> > come out as obtained e.g. by Giannozzi/De Gironcoli/Pavone/Baroni > PRB 1= 991 ?<br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> > nicola<br /> <br /> <br /> <br /> On Mon, 24 May 2010 18:38:31 +0530=EF=BF=BD wrote<br /> <br /> <br /> <br /> >Dear All<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> I have attempted to calculate the specific heat of Si using "F_QHA.x", and = the calculated Silicon phonon dos=EF=BF=BD as an input.<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> (The calculated Si phonon frequencies are in excellent agreement with avail= able experimental data. )<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> ><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 /> <br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> ###########################################################################= #################################<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> <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 /> ><br /> <br /> <br /> <br /> ###########################################################################= #################################<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> #=EF=BF=BD =EF=BF=BD=EF=BF=BD T=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF= =BF=BD=EF=BF=BD E_internal=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD F_vibrati= on=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD Specific heat (C_v)=EF= =BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD=EF=BF=BD Entropy<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> ###########################################################################= #################################<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> :<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> :<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> =EF=BF=BD 295.00=EF=BF=BD =EF=BF=BD =EF=BF=BD 0.0139740852=EF=BF=BD =EF=BF= =BD =EF=BF=BD 0.0055747646=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD=EF=BF=BD 4.6621714979=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF= =BF=BD 4.4956255367<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> 300.00=EF=BF=BD =EF=BF=BD =EF=BF=BD 0.0141222695=EF=BF=BD =EF=BF=BD =EF=BF= =BD 0.0054311560=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD 4.6966380876=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD 4.5= 742737931<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> 305.00=EF=BF=BD =EF=BF=BD =EF=BF=BD 0.0142715257=EF=BF=BD =EF=BF=BD =EF=BF= =BD 0.0052850687=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD 4.7298757363=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD 4.6= 521815403<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> 310.00=EF=BF=BD =EF=BF=BD =EF=BF=BD 0.0144218157=EF=BF=BD =EF=BF=BD =EF=BF= =BD 0.0051365259=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD= =EF=BF=BD 4.7619351485=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD 4.7= 293532915<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> :<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> :<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> :<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> ###########################################################################= #################################<br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> ><br /> <br /> <br /> <br />
