[DFTB-Plus-User] Regarding entropy calculation.

[Jacek Jakowski]

Mermin free energy is a pure electronic energy. It does not have vibrational
entropy but only entropy from electronic smearing.

Jacek

On Fri, Sep 30, 2011 at 1:35 AM, Debasis Koley <debak_mpi at yahoo.com> wrote:

> Dear All,
>
> I have performed QM/MD simulations for 10 ps at 1500K. I am interested in
> getting the free energy
> of the optimized structure and as the output provides the "Mermin Free
> Energy" which is the expression
> of "E-TS". My question is whether the entropy calculated (i.e. S) contains
> vibrational contribution or
> it is purely electronic in nature. Since most of the quantum mechanical
> codes calculates vibrational
> entropy from a harmonic oscillator model, which miserably fails at very
> high temperatures.
> Does DFTB+ calculates the vibrational contribution? and if so does it
> includes any anharmonicity
> corrections at very high temperature.
> Please help me in this regards.
>
> Greetings!
>
> Debasis
>
>
>
> Dr. Debasis Koley
> Assistant Professor,
> Department of Chemical Sciences
> Indian Institute of Science Education and Research, Kolkata
> Mohanpur Campus, PO: BCKV Campus Main Office,
> Mohanpur - 741252, Nadia, West Bengal
> INDIA
> Mail: koley at iiserkol.ac.in, debakmpi at gmail.com
> Mob: ++91-8902326716; ++91-8017529223
> URL: http://www.iiserkol.ac.in/people/faculty/debasis_koley/index.html
>
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>
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