Query is regarding gromacs tutorial for lysozyme simulation

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I am a beginner in MD simulation and i followed the parameter provided for lysozyme simulation. My Rg is same as mentioned in tutorial, however, the RMSD showed huge deviation (5nm) instead of 0.1nm.
Thanks, Aradhya

Probably a PBC effect, have you visualized the trajectory? If the RMSD were actually 5 nm, the protein would have completely unfolded.