The internal structure of rigid bodies change when hybrid using fix rigid/npt/small for rigid bodies rigid and fix nvt for non-rigid bodies

[rainchal]

Thanks Alex. I’ll do some more tests on this. But using timestep of 1 fs and 2fs works well. In my understanding, when I use lj/cut/tip4p/long for all pair interations , this will make other pair atoms search massless charge point as well, similar to tip4p water. This is probably more expensive.