Hi all, my problem in my "by hand' topology remains until now but the errors in atoms of solvent added through genbox command at GMX 3.3.1 disappeared. Unfortnately the variable ci is giving me some headaches and because this I cannot do my topology. Can someone help me in this type of problem? Thanks for your tips Esther but the problem continues to boring me! Thanks all in advance!! **************************************************** Program mdrun_331, VERSION 3.3.1 Source code file:nsgrid.c, line: 226 range checking error: Explanation: During neighborsearching, we assign each particle to a grid based on its coordinates. If your system contains errors that give particles very high velocities you might end up with some coordinates being +- Infinity ou NaN ******************************************************** "Do not wear yourself out to get rich;do not trust your own cleverness. Cast but a glance at riches, and they are gone, for they will surely sprout wings and fly off to the sky like an eagle."(Proverbs 23:4-5) ===========================================