This page could probably be the landing for Overview.
What is it?
PM can be used to compute phonons and their interactions via the lone irreducible derivative (LID) and bundled irreducible derivative (BID) approaches, based on some first-principles method or using empirical potentials.
Given some anharmonic vibrational Hamiltonian, perhaps computed using PM, one can compute various vibrational observables, including phonon lineshifts and linewidths, thermal conductivity, density of states, etc.
Given some real space electronic Hamiltonian, various electronic observables can be computed, including density of states, magnetism within Hartree-Fock (assuming local interactions), etc.
Why do I want it?
Our BID algorithm for computing phonons and their interactions is the fastest finite displacement algorithm allowed by group theory.