share/top/amber99sb.ff/watermodels.dat

   1 tip3p    TIP3P     TIP 3-point, recommended
   2 tip4p    TIP4P     TIP 4-point
   3 tip4pew  TIP4P-Ew  TIP 4-point optimized with Ewald, recommended
   4 spc      SPC       simple point charge
   5 spce     SPC/E     extended simple point charge