Examples¶
treams is a program that covers various aspects of T-matrix calculations and associated topics. The functionality can be roughly separated into three levels: low-level functions, intermediate-level functions, and high-level functions and classes.
The low-level functions implement the underlying mathematical functions, that build
the foundation of T-matrix calculations. They are mainly located in the two subpackages
treams.special and treams.lattice. The first one contains, e.g., the
various solutions to the Helmholtz equation and their translation coefficients, the
second subpackage contains functions that are associated with computations in lattices.
On the intermediate-level those underlying functions are combined to provide functions as they are often needed for T-matrix calculations, e.g., the Mie coefficients or the expansion coefficients of vector plane waves into spherical waves. The low- and intermediate-level functions are mostly focused on speed, they are usually implemented in compiled code and are often vectorized. The latter aspect also helps with the integration into the framework provided by numpy.
The high-level functionality is more focused on the usability. We attempt to create an useful interface to the underlying functions, that reduces redundancy and that is less error prone than using the pure functions, while still integrating nicely with numpy functions. It consists of a combination of different classes and functions. At first, there are the different basis sets, that can be used together with other important parameters for the calculation, for example the embedding materials or the lattice definitions. Then, there are the “physics-aware arrays”, which keep track of these parameters during the computation, and operators that can be applied to these arrays. Finally, we will introduce, how these previous concepts can be applied to T-Matrices for vector spherical and cylindrical solutions and to S-Matrices for vector plane wave solutions.