I encounter the error msg “Bad principal moments” when applying “fix rigid” on a group of atoms.
I’ve found a earlier reply from you saying that highly symmetric rigid body can cause such problem sometimes.
Is there any effective solution for handling this problem if a highly symmetric rigid body (like a spherical tip) is do required to be constructed?
Just try constructing a body with various shapes or size until the lammps accept one of them?
Thanks very much!