I was trying to run dimethyl ether (DME) liquid simulation using CHARMM Drude FF files provided by Mackerell Lab: http://mackerell.umaryland.edu/charmm_drude_ff.shtml
The initial structure is from a 10 ns DME liquid simulation using additive CHARMM FF (all properties match what was reported in the previous paper)
I added Drude particles and lone pairs, then only relaxed Drude particles.
But when I start the liquid simulation I kept getting the error message saying: ** ERROR IN HardWallDrude ** The drude is too far away from atom 16 d = 189.9591
I also tried not relaxing Drude (so the Drude particles initially overlap with their real atoms) but I would get the same error message on a different atom: ** ERROR IN HardWallDrude ** The drude is too far away from atom 1 d = 0.7066
I also tried using several completely different initial configurations, sometimes the simulation won't crash but the volume would increase to an unreasonable value.
Previously, I also encountered the incorrect density problem when I was running Drude w/o lone pairs, but that was caused by too few images and was fixed after I made sure I had 26 images.
But this time I have the correct number of images and my system is still blowing up and most of the time the simulation crashed right in the beginning because the error in hardwalldrude
The setting for the simulation is the same as my previous thread: https://www.charmm.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=37883#Post37883
Is this only caused by my configuration (but it's pre-equilibrated using additive FF) or am I doing something wrong?
Thanks in advance!