title: Exchange-Hole Dipole Dispersion Model for Accurate Energy Ranking in Molecular Crystal Structure Prediction.
abstract: Accurate energy ranking is a key facet to the problem of first-principles crystal-structure prediction (CSP) of molecular crystals. This work presents a systematic assessment of B86bPBE-XDM, a semilocal density functional combined with the exchange-hole dipole moment (XDM) dispersion model, for energy ranking using 14 compounds from the first five CSP blind tests. Specifically, the set of crystals studied comprises 11 rigid, planar compounds and 3 co-crystals. The experimental structure was correctly identified as the lowest in lattice energy for 12 of the 14 total crystals. One of the exceptions is 4-hydroxythiophene-2-carbonitrile, for which the experimental structure was correctly identified once a quasi-harmonic estimate of the vibrational free-energy contribution was included, evidencing the occasional importance of thermal corrections for accurate energy ranking. The other exception is an organic salt, where charge-transfer error (also called delocalization error) is expected to cause the base density functional to be unreliable. Provided the choice of base density functional is appropriate and an estimate of temperature effects is used, XDM-corrected density-functional theory is highly reliable for the energetic ranking of competing crystal structures.
authors.affiliation: Department of Chemistry, Dalhousie University , 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Whittleton
authors.affiliation: Department of Chemistry, University of British Columbia, Okanagan , 3247 University Way, Kelowna, British Columbia V1V 1V7, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Otero-de-la-Roza
authors.affiliation: Department of Chemistry, Dalhousie University , 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2, Canada.
authors.forename: Erin R
authors.identifier: http://orcid.org/0000-0002-5651-468X
authors.initials: ER
authors.lastname: Johnson