You may print out the atomic coordinations of the system and visualize it using Jmol, model, or other software.
....
nlPrint(your_atomic_configuration)
The above line will print out the Cartesian coordinates of atoms, and you may put them in a file with XYZ format.
NLPolicyError :atomic_configuration why
For this error, you had better check the geometry structure of your system, especially for the nearest neighboring distance of atoms. Maybe, some of atoms are too close to each other.