[gmx-users] Problem with 512 membrane

[Du Jiangfeng (BIOCH)]

Dear Gro users,
We created an all-atom system with 512 DPPCs by the method which was suggested by Justin (genconf -f 128.gro -o 512.gro -nbox 2 2 1) and a CG system with 512 DSPCs by using Martini self assembly tutorial. We do get nice bilayers, however after minimization, the systems break apart. 
Also, if we add ions into the system, it also breaks apart. 
Our question is: What  causes the membrane to break apart during the minimization process? does it mean that 512 lipids' system is not stable or is it a minimization method problem?
By the way, the minimization of a 128 lipids system has no problem.

Albert and Jiang.