H2O ice Ih(0001) at 90K

The full-bilayer termination of normal hexagonal (Ih) ice is preferred,
based on total-energy and molecular-dynamics calculations.
The outermost molecules (in layer 1) vibrate so strongly
that the surface looks like a half-bilayer termination to LEED.
Experimental proof of the presence of layer 1 is still needed.
(O atoms are drawn in blue; only some hydrogens -yellow- are shown;
larger spheres represent complete H2O molecules;
the bulk O-O distance is shown.)