Lowest-energy structures of water clusters (H ₂O)n and (H ₂O) ₁₃

We employed a four-step searching/screening approach to determine best candidates for the global minima of (H ₂O) ₁₁ and (H ₂O) ₁₃. This approach can be useful when there exist a large number of low-lying and near-isoenergetic isomers, many of which have the same oxygen-skeleton structure. On the two new candidates for the global minimum of (H ₂O) ₁₁, one isomer can be viewed as placing the 11th molecule onto the side of the global minimum of (H ₂O) ₁₀ and the other can be viewed as removing the 12th molecule from the middle layer of the global minimum of (H ₂O) ₁₂. The three leading lowest-energy clusters of (H ₂O) ₁₃ can all be built starting from the global minimum of (H ₂O) ₁₂, with the difference being in the location of the 13 ^th water molecule. © 2006 American Chemical Society.