Prior to calculating the J(0), Fη, and FR2 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=49] # 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=53] # Define the chemical shift relaxation interaction. value.set(val=-172 * 1e-6, param='csa')
For the angle in degrees between the 15N-1H vector and the principal axis of the 15N chemical shift tensor, the user function call is:
[firstnumber=56] # Set the angle between the 15N-1H vector and the principal axis of the 15N chemical shift tensor value.set(val=15.7, param='orientation')