ENH: ASE-Calculator should be faster and easier to setup
ASE-calculator should handle permutations of clusters in a smart way rather than just enumerating all of them.
Maybe @freeriks can take a look at this since you know these details of permutations, indicies and np.einsum
better than me.
This is important also because currently there is no good way to setup the ASE-calculator since fcm.get_forceconstants
returns the "sparse" fc_dict.
This relates slightly to #18 (closed) , in the sense that in which format do we want to store force constants and how do we convert between different formats? For instance how should you setup an ASE-calculator using phono3py force constants?
Edited by Erik Fransson