Summary

The structure of the lattice_hamiltonian module is illustrated in the above schematic. The core of the code is the Lattice class in the lattice.py file. This class contains all the methods needed to construct the Hamiltonian (generate_uniform and build_ham), find its eigenstates (states_from_ham) and calculate their steady-state populations (get_rates_mat and solve_steady). The methods states_from_ham and get_rates_mat call on helper functions from the files Recombination.py and Redfield.py, respectively, though Recombination.py is only used if const_recombination is set to False (see Section Three).

In addition to the Lattice class, the lattice.py file also contains the Parameter and Site dataclasses. The former contains the values of global variables, such as temperature, which are used in all the other functions and the latter contains the properties of each individual site in the lattice and is called by the generate_uniform method. These sites are then used to define the basis set in which the Hamiltonian is built by the build_ham method.

To see an example of how the lattice class can be instantiated and used, refer to the RunLattice.py file. If you would like to try running the code, you can use the WorkedExample.ipynb file to see how changing the electronic coupling affects the energies and distributions of the system's eigenstates.