Prior to calculating the J(ω) values, the physical interactions which govern relaxation of the spins must be defined. For the magnetic dipole-dipole relaxation interaction, the user functions are:
[firstnumber=21] # Define the magnetic dipole-dipole relaxation interaction. interatom.define(spin_id1='@N', spin_id2='@H', direct_bond=True) interatom.set_dist(spin_id1='@N', spin_id2='@H', ave_dist=1.02 * 1e-10)
For the chemical shift relaxation interaction, the user function call is:
[firstnumber=25] # Define the chemical shift relaxation interaction. value.set(val=-172 * 1e-6, param='csa')