Multistage Optimization Workflow

Running QM computations can be very expensive, and it is important to find the combination of methods that produces the best possible results in the shortest amount of time. Rowan's multistage optimization workflow provides Pareto optimal combinations of methods that span the fast to accurate frontier. These modes cover all of the first 86 elements in the periodic table and are excellent for computing the geometries and energies of molecules, non-covalent interactions, and transition states.

Since optimizations are significantly more expensive than single points, and a majority of the error comes from the single point energetics, it is possible to use a quick method for the optimization and use a more accurate method for just the singlepoint. In particular, semi-empirical methods can be very good for computing accurate geometries, but are much less accurate for energetics.

Rowan provides four modes for multistage optimization:

• RECKLESS is useful for quick optimizations and to obtain a general sense of the chemical landscape.
• RAPID works well for most chemical problems and provides a good balance between speed and accuracy.
• CAREFUL provides publication quality results, but is significantly more expensive due to the DFT optimization.
• METICULOUS provides the highest accuracy, but is significantly more expensive due to the use of a range-separated DFT functional for the optimization and a large basis set for the single point energy.

In general, RAPID mode is recommended for most systems, while CAREFUL is recommended for producing final, publication-quality results. METICULOUS is recommended only for systems where the highest accuracy is required.

Modes