[Pw_forum] Error in QHA calculations

[bramha pandey]

Dear Denis,
Firstly you have to check your Phonon dos norm is coming correct or not???
I think there is a problem calculating with phonon frequency(Omega).
Here i am giving you a reference from where you can get the important clue.

""""First-principles calculations of phonon and thermodynamic properties
of AlRE (RE= Y, Gd, Pr, Yb) intermetallic compounds ∗
Rui Wang† Shaofeng Wang, and Xiaozhi Wu""""""
,



Department of Physics and Institute for Structure and Function, Chongqing
University,
Chongqing 400044, P. R. China.


On Mon, Jul 30, 2012 at 2:57 PM, DENIS MAGERO <magerode at gmail.com> wrote:

> Dear all,
> I,m calculating thermodynamic properties using QHA for magnesium hydride.
> There is however a value of NaN for values of entropy and F_vibration.
> Could someone please help.
>
> Attached is the file.
>
> # Zero vibration energy:      0.0053709107  (Ry/cell)
> # Phonon DOS norm      :      1.998766      ! 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      0.0053761511               NaN
> 0.0024038079                   NaN
>    10.00      0.0053762656               NaN
> 0.0048307667                   NaN
>    15.00      0.0053764576               NaN
> 0.0073049072                   NaN
>    20.00      0.0053767292               NaN
> 0.0098829693                   NaN
>    25.00      0.0053770872               NaN
> 0.0128304742                   NaN
>    30.00      0.0053775527               NaN
> 0.0168191020                   NaN
>    35.00      0.0053781734               NaN
> 0.0227957550                   NaN
>    40.00      0.0053790267               NaN
> 0.0316241179                   NaN
>    45.00      0.0053802120               NaN
> 0.0438189128                   NaN
>    50.00      0.0053818386               NaN
> 0.0594854231                   NaN
>    55.00      0.0053840137               NaN
> 0.0783989719                   NaN
>    60.00      0.0053868337               NaN
> 0.1001298120                   NaN
>    65.00      0.0053903795               NaN
> 0.1241557017                   NaN
>    70.00      0.0053947154               NaN
> 0.1499421117                   NaN
>    75.00      0.0053998891               NaN
> 0.1769907068                   NaN
>    80.00      0.0054059335               NaN
> 0.2048639362                   NaN
>    85.00      0.0054128686               NaN
> 0.2331939897                   NaN
>    90.00      0.0054207041               NaN
> 0.2616824973                   NaN
>    95.00      0.0054294410               NaN
> 0.2900952630                   NaN
>   100.00      0.0054390741               NaN
> 0.3182546901                   NaN
>
>
> --
> Dennis Magero,
> M.Sc Student,
> Computational group,
> Chepkoilel University College, ELDORET
> KENYA.
>
>
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>
>


-- 
Thanks and Regards
Bramha Prasad Pandey
Ph.D Student Indian School of Mines(ISM)
Dhanbad, INDIA.
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