# Gibbs2

Gibbs2 is a program for the calculation of thermodynamic properties in periodic solids under arbitrary conditions of temperature and pressure. Gibbs2 uses the results of periodic solid-state quantum-mechanical calculations, specifically the energy-volume curve and possibly the harmonic phonon frequencies, to compute the thermodynamic properties of the solid within the framework of the quasiharmonic approximation.

• You can download the current version of the gibbs2 program from:
gibbs2-1.0.zip.

Alternatively, clone the git repository for the latest version of the code:

git clone https://github.com/aoterodelaroza/gibbs2.git


or visit the github page.

## Features

• Predict thermodynamic properties of periodic solids from energy-volume curves calculated using first-principles methods.

• Various equations of state can be used to fit the calculated E(V) points and obtain the pressure and the enthalpy.

• Different thermal models can be used to incorporate the effects of temperature: From the simple Debye model, which requires only the E(V) curve, to the full quasiharmonic approximation that uses the phonon density of states at each volume.

• Computes all relevant thermodynamic properties: bulk moduli, heat capacities, entropies, free energies, thermal expansivity coefficients, etc. All of them as a function of pressure and temperature.

• Can be used on multiple phases. When more than one phase is input, gibbs2 calculates phase stability based on G(p,T) and predicts the phase diagram.

## Files

• LICENSE: a copy of the licence. Gibbs2 is distributed under the GNU/GPL license v3.
• src/: source code. The gibbs2 binary is generated in here.
• tests/: a few examples that also serve as regression tests for the program.

## Citation

The basic references for gibbs2 are:

Please cite these if you find this program useful. See the outputs and the manual for references pertaining particular keywords.

Gibbs2 is distributed under the GNU/GPL v3 license. The LICENSE file in the root of the distribution contains a copy of the license.