MedeA® Gibbs : Thermodynamics of fluids and adsorption

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

Datasheet: 

materials_design_gibbs_datasheet.pdf