Step 2 - Apply a Forcefield

Time to tell our Cu-BTC how to move! There are lots of forcefields out there for metal organic frameworks, with varying complexity and functional form. Dissolve implements a few of them for specific cases, and we’ll use the one by Zhao et al..

Click on the   Cu48O192C288H96   species tab

Species ⇨ Add Forcefield Terms…

From the available forcefields choose Zhao2010 and click Next

You can filter forcefields by keywords in name and description by using the filter box at the top-right of the forcefield selection controls.

We will use the default Determine atom types for all atoms option to add atom types for every atom in the species, so click Next

Here you’ll see that there are some conflicts with atom types assigned during the CIF import - we will simply overwrite them with those from the forcefield, so click Next

For the intramolecular terms we want to assign them and reduce to master terms (the default settings) so click Next to proceed

There will be no conflicts with existing master terms, so click Finish to exit the wizard

Our forcefield for the MOF is now ready, but because we’re only treating the unit cell (rather than a supercell) we need to reduce the pair potential range since the default (15.0 Å) is longer than the half-cell length of the Cu-BTC unit cell ($l$ = 26.3336 Å):

Go to the   Forcefield   tab, Pair Potentials section

In the controls, change the Range from 15.0 to 12.0

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