Corrections

It's frequently benefical to add post hoc corrections to mean-field calculations to compensate for certain inaccuracies in the theory. Rowan supports use of Grimme's empirical "D3" dispersion correction, which has been shown to dramatically improve the performance of Hartree–Fock and density-functional theory calculations (e.g.).

For now, Rowan only supports the D3 correction with Becke–Johnson damping (with the exception of the geometric counterpoise and short-range basis corrections performed internally for composite methods). This correction can be requested by adding the keyword d3bj to the corrections list:

import cctk
import rowan

rowan.api_key = "rowan-SK"
client = rowan.Client()

# load molecule by name
molecule = cctk.Molecule.new_from_name("cyclopentane")

# run calculation remotely and return result
result = client.compute(
    molecule,
    name="opt cyclopentane",
    method="b3lyp",
    basis_set="6-31G*",
    corrections=["d3bj"],
    tasks=["optimize", "frequency"]
)

For instructions on how to select corrections when submitting calculations using the web interface, see the web interface documentation.