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