4  ! nsite (number of sites in each rigid body)
 0.000000d0   0.068927d0   0.000000d0    !O site--> 1
 0.756950d0  -0.516955d0   0.000000d0    !H site --> 2
-0.756950d0  -0.516955d0   0.000000d0    !H site --> 3
 0.000000d0  -0.081073d0   0.000000d0    !X site --> 4

