title: Deleterious Effects of Exact Exchange Functionals on Predictions of Molecular Conductance.
abstract: Kohn-Sham (KS) density functional theory (DFT) describes well the atomistic structure of molecular junctions and their coupling to the semi-infinite metallic electrodes but severely overestimates conductance due to the spuriously large density of charge-carrier states of the KS system. Previous works show that inclusion of appropriate amounts of nonlocal exchange in the functional can fix the problem and provide realistic conductance estimates. Here however we discover that nonlocal exchange can also lead to deleterious effects which artificially overestimate transmittance even beyond the KS-DFT prediction. The effect is a result of exchange coupling between nonoverlapping states of diradical character. We prescribe a practical recipe for eliminating such artifacts.
authors.affiliation: Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States.
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Feng
authors.affiliation: Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamada
authors.affiliation: Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel.
authors.forename: Roi
authors.initials: R
authors.lastname: Baer
authors.affiliation: Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States.
authors.forename: Barry D
authors.initials: BD
authors.lastname: Dunietz