Seminarium Fizyki Materii Skondensowanej

Water is known to form ~20 different solid phases. In many of them the orientations of water molecules in crystal lattice are disordered which leads to residual entropy as T -> 0. This configurational entropy has only been calculated exactly for 2D ice model on square lattice (Lieb, 1967). For 3D ice models on hexagonal (ice-Ih) and cubic (ice-Ic) lattices, their residual entropies have been estimated by Pauling (1932) and improved by Nagle and Onsager (1966) but since then there was no noticeable improvement neither in analytic results nor in numerical calculations. This left some unresolved questions, which I will address during the talk.