22.5; phase shifts, 22.4; *scattering.py* Path integral, **31.1**--31.4; free particle, 31.2; harmonic oscillator, 31.3; *path_integral.py* Pauli exclusion principle, **15.3**, 16.1 Pauli matrices, **13.2**; algebra, 13.2; properties, 13.2 Periodic potential, **26.1**--26.2 Periodic table, **16.1**-