gcmc - Non-numeric positions - simulation unstable


I have determined that the simulation was crashing due to fix shake on the inserted waters.

Does anyone know if there is a problem with using fix shake for gcmc?

My input script:

It is not surprising, that it is more difficult to get a stable simulation, especially, if you have a dense system. When you apply fix shake, you are making it harder to insert a particle, as it is more likely to have very high forces, which might cause an overflow and troubles due to floating point math limitations and the fact that the shake algorithm may not fully converge.

Not sure what to recommend. You may try to change mu to insert less aggressively, or you may also try to use soft-core potentials (e.g. from USER-FEP) to avoid diverging forces at short distances, or switch to a flexible water potential or a combination of those.


I switched to a flexible water potential. Thanks Axel

fix shake works correctly with gcmc if you follow the provided example closely…examples/in.gcmc.h2o