What and Why
The simple operator exponentiation as done in [#213] is not enough to use any but the most trivial operators in real applications (absorbing boundary conditions, split operator), because these are usually composed of multiple operators. This issue should improve the situation somewhat.
The following issues need to be addressed:
- Realistic operators are usually composed of multiple operators (e.g., a product of one-dimensional potentials). A first step towards exponentiation must hence be to simplify/squeeze the input operator, see [#214].
- After squeezing, a typical operator may consist of an electric field and some dipole function. We must be able to identify and exponentiate such specific operator products.
- In many realistic applications, we may have a coordinate-dependent transition dipole moment that couples multiple states / channels. We must be able to identify such a situation and exponentiate the corresponding operator. This is not strictly required for some applications, so it may be put into a followup issue.
