Designing GhostFragment’s FragmentedSystem Driver

The purpose of this page is to capture the design process of GhostFragment’s FragmentedSystem Driver.

What is a FragmentedSystem Driver?

In our design, the FragmentedSystem driver is charged with going from the input chemical system, to the final set of (sub-) chemical systems.

FragmentedSystem Driver Considerations

Accuracy

From Designing GhostFragment’s Input Driver we know the FragmentedSystem driver is responsible for creating the final set of subsystems and must be able to determine those subsystems in a manner which accounts for all important interactions.

Hierarchical

The ChemicalSystem class is a hierarchical class. The FragmentedSystem class is also hierarchical. Being able to create a hierachical driver allows us to mirror the hierarchical structure found in both the inputs and the results.

• Ultimately fragments are defined by the nuclei. Exactly how the fragments are formed is decoupled from the process of creating a FragmentedSystem by having the inputs be an already created FragmentedNuclei object.

Embedding.

From Hierarchical we note that the field component of the ChemicalSystem class is the new component relative to the Molecule class. The FragmentedSystem driver should then be responsible for assigning fields to each subsystem in a FragmentedMolecule instance.

FragmentedSystem Driver Design

Fig. 5 High-level overivew of the components of the FragmentedSystem driver.

Fig. 5 shows the high-level design of the Fragmentedsystem driver. Because of Hierarchical the first step of the driver is to form a FragmentedMolecule (the class one rung lower in the FragmentedSystem hierarchy) from the input FragmentedNuclei and supersystem. The next step of the driver is to determine a field for each fragment in the FragmentedMolecule, which in turn addresses consideration Embedding..

At this stage, consideration Accuracy is primarily punted to the FragmentedMolecule driver, although the field driver is able to recover some of the electorstatic and potentially polarization effects missed by the fragments.