# [Pw_forum] problem to convert Cv (R) to Cv(in J/mol.K)

bramha pandey pandey.bramha at gmail.com
Thu Feb 2 11:40:38 CET 2012

```Sorry to disturbing all of you.
But Really i need your's help to understand the the following
through the F_QHA.X code.

# Zero vibration energy:      0.0000000005  (Ry/cell)
# Phonon DOS norm      :      0.000000      ! 3N for check purpose, N
number of atoms in the unit cell
# T in K, F_vib in Ry/cell, C_v in R (the universal gas constant by 3N
modes), S in k_B
#
#   T         E_internal        F_vibration          Specific heat
(C_v)       Entropy
############################################################################################################
5.00      0.0000000005      0.0000000005           0.0000000000
0.0000000000
10.00      0.0000000005      0.0000000005           0.0000000000
0.0000000000
15.00      0.0000000005      0.0000000005           0.0000000001
0.0000000000
20.00      0.0000000005      0.0000000005           0.0000000002
0.0000000001
25.00      0.0000000005      0.0000000005           0.0000000004
0.0000000001
30.00      0.0000000005      0.0000000005           0.0000000010
0.0000000002
35.00      0.0000000005      0.0000000005           0.0000000020
0.0000000005
40.00      0.0000000005      0.0000000005           0.0000000036
0.0000000008
45.00      0.0000000005      0.0000000005           0.0000000059
0.0000000014
50.00      0.0000000005      0.0000000005           0.0000000090
0.0000000021
55.00      0.0000000005      0.0000000005           0.0000000128
0.0000000032
60.00      0.0000000005      0.0000000005           0.0000000172
0.0000000045
65.00      0.0000000005      0.0000000005           0.0000000223
0.0000000060
70.00      0.0000000006      0.0000000005           0.0000000278
0.0000000079
75.00      0.0000000006      0.0000000005           0.0000000338
0.0000000100
80.00      0.0000000006      0.0000000005           0.0000000402
0.0000000124
85.00      0.0000000006      0.0000000005           0.0000000468
0.0000000150
90.00      0.0000000006      0.0000000005           0.0000000537
0.0000000179
95.00      0.0000000006      0.0000000005           0.0000000607
0.0000000210

Now sir question remain same how i will get the Cv value in J/Mol.K from R.?

Your valuable help is needed to me.

On Wed, Feb 1, 2012 at 9:54 PM, bramha pandey <pandey.bramha at gmail.com> wrote:
>
>
> Hi..Dear  QE users
>
> I have a problem to calculate the Cv value in J/mol.K from Cv(R gas constant). At 300K, the value of Cv is  0.0000002506 . I multiplied  0.0000002506  by 3NR(3*2*8.314) which comes 1.25*10^-5 which was very less compare to experimental Cv value.
>
> --
> Thanks and Regards
> Assistant Professor (Electronics and Communication Engg)
> GLA Group of Institutions, Mathura.
> Ph. No. 08954143009
> email id pandey.bramha at gmail.com
>             bpglaitm at yahoo.co.in

--
Thanks and Regards