Broadly speaking, there are two main varieties of OQS dynamics; Markovian and non-Markovian. The memory of a system, with respect to the state of the bath, is formalised through the Markov property which itself is a statement that a stochastic process is memoryless if its evolution is independent of its history. When considering an evolution, the classical Markov property asserts that each state at a particular time depends solely on the previous state in time. This means that any process which evolves following a scheme such that successive steps depend on more than the previous time step (i.e. are dependent on the history of the bath) are termed non-Markovian and do not satisfy the Markov property. However, more formal definitions exist related to the divisibility of quantum dynamical maps. These formal definitions lead to identification of quantum Marko- * garth.jones@uea.ac.uk vianity in relation to the flow of information between the system and the bath. In Markovian cases, information flows unidirectionally out of the system and into the bath throughout the entire trajectory. On the other hand, non-Markovian cases include information flow from the bath back into the system, a processes referred to as recurrence. We highlight the work of Li et al. for a rigorous overview of different definitions of non-Markovianity. There have been a number of procedures that have been developed for modelling non-Markovian OQS. In this work we are focused on the hierarchical equations of motion (HEOM), which is a nonperturbative approach derived from path integrals that has been proven to be highly successful in capturing quantum thermal effects in OQS, such as relaxation of a quantum state, by comparison with analytical models. Recently the HEOM has found use in the dynamics of excitons , studies of electron transfer, and excited state dynamics within the condensed phase .