Understanding the impact of ammonium ion substitutions on heterogeneous ice nucleation
Experimental work has found that when ice nucleates on feldspar (a mineral dust common in the atmosphere), it nucleates at a higher temperature in the presence of ammonium ions. Recent work by Tom Whale hypothesised that this was due to an increase in configurational entropy.
In this work, a collaboration with Tom and due to be presented at the forthcoming Water at Interfaces Faraday Discussion, we computationally investigate whether including an ammonium ion in ice increases the configurational entropy, and if this is energetically stable. We find that at reasonable negative surface charges (as may be expected from feldspar) energetically stabilise the region where ammonium inclusions increase the configurational entropy. Have a look at the paper online or grab a pdf here.