Follow-up Comment #7, bug #24131 (project relax): To add on my earlier comment: When encountering a spin without data, I get the above error message about missing interatomic interaction. If I define interactions with: interatom.define(spin_id1='@N', spin_id2='@H', direct_bond=True) the routine gets blocked on encountering the spin with data: RelaxError: The magnetic dipole-dipole interaction already exists between the spins '#1ogt-hkca_mol2:7@N' and '#1ogt-hkca_mol2:7@H'. So either way it doesn't work and I'm stuck … _______________________________________________________ Reply to this item at: <http://gna.org/bugs/?24131> _______________________________________________ Message sent via/by Gna! http://gna.org/