Quasi-one-dimensional ice

The seams CLI has no prism command. Confined ice (nanotube and monolayer) is the confined-ice howto: pydseams.Frame.find_prisms / monolayer_rings, or the yodaStruct Lua examples under example_lua/iceNanotube/. Bulk CHILL+ and cages on the in-tree dump are the mixed TIP4P tutorial.