[DFTB-Plus-User] about total energy

王翠红 cuihong at mail.ustc.edu.cn
Wed Aug 3 03:46:10 CEST 2016

Hi Ben,
Thank you very much for your answer, it is very helpful for me.

在 2016-08-02 05:41:43,"Ben Hourahine" <benjamin.hourahine at strath.ac.uk> 写道:

>Hello Cuihong,
>The total energy is the sum of the electronic and repulsive potential
>energies (and dispersion if present). The Mermin free energy includes
>the electronic entropy, but no other contributions. The Helmholtz energy
>(printed out for non-zero pressure) is the Mermin energy plus pV.
>To get an estimate of the Gibbs free energy, methods such as umbrella
>sampling, thermodynamic integration, harmonic approximations or REMD are
>required. These are not currently supported within DFTB+, but can be
>accessed via some of the codes that can externally drive DFTB+. These
>include i-Pi (an interface will be available in the 1.3 DFTB+ release)
>or ASE.
>On 30/07/16 05:19, 王翠红 wrote:
>> Hello everyone,
>>      I have a question about the Total energy, what is the meaning of total energy? Is it the free energy or the potential energy? If it is the free energy, assuming no change in temperature (T) and volume, the change in free energy is given by delG = delH - T.delS, where delH is equivalent to the change in internal energy, and delS represents the entropic change in the system. Is it only considered the delH?
>> Thank you very much.
>> Best,
>> Cuihong
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