[lammps-users] SPC/E water with SHAKE

Hello all,
I am trying to simulate SPC/E water + 1 ion pair(K+Cl-) using SHAKE alogrithm for constraining bond and angle in water. I used the following input script

Have you done viz on your system? Are the 2 components (water
and other) moving as expected? Can you thermostat them individually
instead of together? If you can't figure it out and your data file is
small, please post it.


Dear sir,
I visualized the system for 2ps . I see that there are only few molecules that are moving and also I see some ordered structure. I thermostated the two components ( water and ions) seperately, I did not see any difference. Please help me in figuring out. (I attached my data file to this email).



data.kcl_shake (241 KB)

Hi Scrinivas,

I looked at your data file. It seems you mislabeled the atoms. E.g. in the “atoms” entry, you define atom 2 is oxgen and atom 1 and 3 are hydrogen, but in the “bonds” entry, you connect atom 1 and 2 (this is correct), atom 1 and atom 3 (this is wrong).


hai ming,
Thank you very much for your reply…
I corrected my mistake. Now it is working.