SAFT-γ Mie, bottled

SAFT-γ Mie, bottled

The SAFT-γ Mie force field is a powerful approach to coarse-grained molecular dynamics: the parameters for the model of a substance are computed from its thermophysical properties, removing the need for tuning models to atomistic simulations. The theory also provides a corresponding equation of state. Here we make the power accessible to anyone.

The bottle

"The bottle" is our collection of 6000+ molecules for which we have already computed the force field parameters. You can search by CAS number, name, or chemical formula.

Search the bottle

Press your own

You can create your own model by providing critical properties for the compound you want to study. The M&M correlation instantly gives you the force field parameters.

Run your own compound

Heteronuclear models

We're hoping to extend this such that you can draw the molecule you want. This feature is still work in progress, for now we just have a demo of the interface that gives you back the SMILES.

Build with the blocks

The theory

The SAFT-γ Mie force field forms part of an established top-down coarse graining methodology that enables molecular dynamics simulations of a wide range of components in the vapor and liquid states [1].

This page produces the force field parameters for a given chemical component, based on the M&M correlation [2] which has been applied to over 7800 compounds, using available critical data from Yaws' book of thermodynamical properties [3]. After filtering the results to ensure their consistency, we are left with over 6000 compounds.

As with all correlations there are caveats. Using the present data set, the biggest hurdle is that one of the inputs to the correlation, namely the liquid density at T=0.7 Tc, is estimated using a Rackett-type equation. For increased accuracy the user is urged to input a better estimate for the liquid density. If the compound you are looking for is not in our database, you may "press" your own given the acentric factor and critical properties.

The parameters produced by this page are for homonuclear models, i.e. a given molecule is made up of m beads linked as on a pearl-necklace with all beads equal. Heteronuclear models may be constructed from a group-contribution approach [4]. However, extra care should be taken to validate such models, especially the cross-interactions between different segments. The Lafitte combination rules [5] provide a useful starting point for the cross-interactions parameters both for mixtures of compounds as well as for heteronuclear models. To test and tune the cross-interactions, there is no substitute for fitting to macroscopic thermodynamic properties. A set of links to reviews on the background SAFT equation of state, and recent papers on the application of the SAFT-γ Mie force field can be found here.

References

[1] Erich A. Müller and George Jackson. Annu. Rev. Chem. Biomol. Eng. 5 (2014): 405-427.
[2] Andrés Mejía, Carmelo Herdes and Erich A. Müller. Ind. Eng. Chem. Res. 53.10 (2014).
[3] Carl L. Yaws. "Thermophysical properties of chemicals and hydrocarbons (Electronic Edition)". Knovel, 2010.
[4] Vasileios Papaioannou, Thomas Lafitte, Carlos Avendaño, Claire S. Adjiman, George Jackson, Erich A. Müller and Amparo Galindo. J. Chem. Phys. 140 (2014).
[5] Thomas Lafitte, Anastasia Apostolakou, Carlos Avendaño, Amparo Galindo, Claire S. Adjiman, Erich A. Müller and George Jackson. J. Chem. Phys. 139 (2013).