[DFTB-Plus-User] Regarding entropy calculation.

Debasis Koley debak_mpi at yahoo.com
Fri Sep 30 07:35:40 CEST 2011

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.



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
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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