  Ice nucleation plays a significant role in a large number of natural and
technological processes, but it is challenging to investigate experimentally
because of the small time (ns) and short length scales (nm) involved. On the
other hand, conventional molecular simulations struggle to cope with the
relatively long timescale required for critical ice nuclei to form. One way to
tackle this issue is to take advantage of free energy or path sampling
techniques. Unfortunately, these are computationally costly. Seeded molecular
dynamics is a much less demanding alternative that has been successfully
applied already to study the homogeneous freezing of water. However, in the
case of heterogeneous ice nucleation, nature's favourite route to form ice, an
array of suitable interfaces between the ice seeds and the substrate of
interest has to be built - and this is no trivial task. In this paper, we
present a Heterogeneous SEEDing approach (HSEED) which harnesses a random
structure search framework to tackle the ice-substrate challenge, thus enabling
seeded molecular dynamics simulations of heterogeneous ice nucleation on
crystalline surfaces. We validate the HSEED framework by investigating the
nucleation of ice on: (i) model crystalline surfaces, using the coarse-grained
mW model; and (ii) cholesterol crystals, employing the fully atomistic
TIP4P/Ice water model. We show that the HSEED technique yields results in
excellent agreement with both metadynamics and forward flux sampling
simulations. Because of its computational efficiency, the HSEED method allows
one to rapidly assess the ice nucleation ability of whole libraries of
crystalline substrates - a long-awaited computational development in e.g.
atmospheric science.
