Step 1b - Add Isotopologues

We have three experimental datasets in this example - H₂O, D₂O, and a 50:50 mix of the two. The natural isotopologue (H₂O) is defined automatically by Dissolve, so we don’t need to add it by hand. We will need to add a new one for D₂O, but that is all. Mixtures (e.g. the H₂O:D₂O 50:50 sample) are created by blending isopologues, rather than defining specific isotopologues for the desired isotope ratios, and will be done when we set up the NeutronSQ modules.

Go to the   Water   species tab, and click the   Isotopologues   section

Click Add

This will create a new isotopologue containing every atom type in the species, defaulting to the natural isotope mix

Change the isotope for the HW atom type from Natural (bc = -3.739 fm) to 2 (bc = 6.671 fm)"

Change the name of the isotopologue to ‘Deuterated’ (double-click on the name to do so)

Users familiar with EPSR might expect to also set any exchangeable atoms here in the isotopologue definitions, but in Dissolve this is handled by specific settings in individual modules.

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