请问跑动力学得到WARNING: negative index -1 in group LI是怎么回事？

yihanxu

老师好，大家好，跑em和md时都得到了两个WARNING: negative index -1 in group LI，请问是怎么回事？谢谢。
信息原文如下：

Command line:
  gmx grompp -f em.mdp -c solvate_ppy_cent.pdb -p solvate_ppy_cent.top -o em.tpr -maxwarn 1 -n index.ndx

Setting the LD random seed to -475084323
Generated 91 of the 91 non-bonded parameter combinations
Generating 1-4 interactions: fudge = 0.5
Generated 91 of the 91 1-4 parameter combinations
Excluding 3 bonded neighbours molecule type 'ppy'
Excluding 3 bonded neighbours molecule type 'S4'
Excluding 1 bonded neighbours molecule type 'LI'
Excluding 3 bonded neighbours molecule type 'DME'
Excluding 3 bonded neighbours molecule type 'DOL'
Removing all charge groups because cutoff-scheme=Verlet


WARNING: negative index -1 in group LI




WARNING: negative index -1 in group LI

Number of degrees of freedom in T-Coupling group rest is 97881.00
Estimate for the relative computational load of the PME mesh part: 0.46

GROMACS reminds you: "Check Your Output" (P. Ahlstrom)

yihanxu

我开始建的结构有问题，体系有一部分处在盒子界定的范围之外，即盒子和体系之间有个平移，体系的中心（含两个Li离子）刚好处在盒子原点，改了之后就没那种warning了，不知道是为什么？