MedeA® GIBBS : Thermodynamics of fluids and adsorption

Compute thermophysical properties of single and multi-phase fluids as well as adsorption isotherms of fluids on solids, based on Monte Carlo method with interatomic interactions described by forcefields.

MedeA-Gibbs is the result of a joint development of the IFP Energies Nouvelles, the CNRS, and Université Paris Sud. It is integrated in the MedeA platform with a convenient user interface and analysis tools.

MedeA GIBBS : Thermodynamics of fluids and adsorption

Using Gibbs to Explore Methane Adsorption to Carbon Nanotubes
Using MedeA-Gibbs to Explore Methane Adsorption to Carbon Nanotubes.
In this example we will look at how the Gibbs module can provide insight into methane adsorption to carbon nanotubes. The MedeA nanotube builder greatly simplifies the creation of structures and can create any possible carbon nanotube - whether single or multi-walled. Setting up calculations using MedeA flowcharts eliminates the need to manually create input files - simplifying the process for running Gibbs calculations to a few easy steps.

Properties from GIBBS:

  • Phase properties:
    Volumetric (density, molar volume), virial pressure, cohesive energy chemical potential (or fugacity), residual heat capacity, compressibility, thermal expansivity, Joule-Thomson coefficient

  • Phase equilibria of pure compounds:
    Vapor pressure, vaporization enthalpy

  • Phase equilibria of binary and multicomponent systems:
    Phase compositions, phase densities, cohesive energy

  • Adsorption:
    Amount adsorbed of each species, guest-host energy, integral heat of adsorption

Simulation conditions available from GIBBS:

  • Single phase fluid calculations (NVT, NPT statistical ensembles)

  • Two-phase and three-phase fluid equilibria (Gibbs Ensemble Monte Carlo)

    • At imposed global volume (pure compounds, binary and multicomponent systems)

    • At imposed pressure (binary and multi-component systems)

  • Simulation of adsorption in microporous crystalline solids (Grand canonical ensemble)

Key benefits of GIBBS:

  • Explicit account of molecular shape, flexibility, and polarity to compute thermodynamic properties from first principles
  • Use of well-tested forcefields
  • High extrapolation capacity in temperature and pressure
  • Simulation of pure component properties (toxic, unstable,…) from molecular structure only
  • Simulation of multicomponent fluid properties without empirical coefficients for mixing rules
  • Understanding of fluid adsorption behavior as a result of the microstructure of the adsorbent and fluid composition
  • Calculation of liquid-vapor critical points
    without classical pitfalls
  • Contribution of the various forms of energy to fluid properties

Computational characteristics

  • Two methods for long range corrections to electrostatic energy (reaction field, Ewald summation)
  • Allows rigid molecules, flexible molecules (linear, branched, cyclic) with electrostatic charges

  • Adsorption :

    • Edition of microporous crystalline solids of various space groups from databases (ICSD, Pearson, Pauling) through MedeA visual builder

    • Cubic, orthorhombic and non- orthogonal simulation boxes

    • Pre-calculation of energy grids for high computational efficiency

  • Featuring major forcefields for fluid properties: OPLS-UA, TraPPE, AUA

  • 14 different Monte Carlo moves for the efficient sampling of internal and intermolecular configurations (configurational bias, rotational bias, etc.)

  • Runs either locally or on remote server through JobServer + TaskServer MedeA architecture Parallelization of energy calculations by Open-MP

Required MedeA modules:

  • Core MedeA environment
  • JobServer and TaskServers
  • Forcefields