# [Pw_forum] How we can give Temperature to equilibrium system (T=o)

bramha pandey pandey.bramha at gmail.com
Fri Feb 10 17:08:14 CET 2012

```Dear GAO Zhe and QE users...Thanks alot  for your quick reply.

I have calculated the phonon DOS value and by fqha.x utility which is given
in PH/fqha.x. I have calculated the free energy F(T) at different
temperature.
The normalised phonon 3*N=6.00011 getting which is right.(i am taking 2
atoms in unit cell as FCC in zincblende structure). the Desprsion relation
of frequency and PHDOS graph was also seems right.

But realy i want to calculate Specific heat (C_v), Entropy. so for that i
was tried for  QHA package which was given in QE, but it is not giving the
accurate value and very less value i was getting in order of 10^-7 of Cv.
Here i an attaching the PHDOS.out file please see it.

other thermodynamical parameters.

I am heartily appreciated any help regarding this problem.

2012/2/9 GAO Zhe <flux_ray12 at 163.com>

> You can obtain thermodynamics properties at finite temperature by
> calculating phonon (ph.x) and treating phonon through QHA method. If
> temperature was high, you may need an-harmonic calculation by d3.x
>
> --
> GAO Zhe
> CMC Lab, Materials Science & Engineering Department,
> Seoul National University, South Korea
>
>
> At 2012-02-09 22:49:27,"bramha pandey" <pandey.bramha at gmail.com> wrote:
>
>
> Dear QE users...
>
> i want to know how we can introduce the temperature in our equilibrium
> system(i.e after running scf with proper setting of lattice parameter, ecut
> and k point, we get ground state total energy(T=0) in scf run).
>
> As i read somewhere that SCF will gives the minimum total energy at T=0,
> because in DFT there is no term of temperature.
> May be i am wrong but can we introduce temperature  by changing the any
> parameter in input file of pw.x.  Actualy i want to generate the  phonon by
> the thermal excitation  in my input file by increasing the temperature of
> my system or any other means by which i can generate  phonon for
> thermo-dynamical  property calculation of the system.
>
> Any type of help will be appreciable .
>
>
> --
> 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
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
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