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Manuscript Title: GIBBS: isothermal-isobaric thermodynamics of solids from energy curves using a quasi-harmonic Debye model.
Authors: A. Blanco, E. Francisco, V. Luana
Program title: GIBBS
Catalogue identifier: ADSY
Journal reference: Comput. Phys. Commun. 158(2004)57
Programming language: Fortran 77.
Computer: Intel Pentium, Alpha, Sun Sparc/Ultra/Blade.
Operating system: Unix, GNU/Linux.
RAM: 200K words
Word size: 32
Keywords: Equation of state, Quasi-harmonic Debye model, Solid state physics, Lattice Dynamics.
Classification: 7.8.

Nature of problem:
Derivation of the static and thermal equation of state, chemical potential, and thermodynamic properties of a crystal from energy volume data only.

Solution method:
A quasi-harmonic Debye model is used to obtain the vibrational Helmholtz free energy as a function of temperature at the molecular volumes of input. The non-equilibrium Gibbs energy is then minimised at any temperature T and pressure p to obtain the EOS and the chemical potential. Several standard EOS parameters can be derived by fitting analytical forms to the pressure-volume data. Finally, some thermodynamic properties are computed for each (p,T).

Thermal effects are assumed to be well represented by a quasi-harmonic Debye model, in which the temperature dependence of the internal parameters is embedded into the temperature dependence of the volume.

Running time:
Less than 1 second (Pentium III, 800 MHz) for 25 (E,V) pairs, 10 pressure and 10 temperature values.