2014/05/27 by Ioan Bâldea, Ioan Baldea · 55 citations
Chemistry · Engineering · Physics and Astronomy · #Atomic orbital #Atomic physics #Basis set #Chemical physics #Chemistry #Electrochemical Analysis and Applications #Electrode #Electron #Ion #Ionization #Molecular Junctions and Nanostructures #Molecular physics #Molecule #Organic Electronics and Photovoltaics #Physical chemistry #Physics #Quantum #Quantum mechanics #physics.chem-ph #physics.comp-ph
paper · pdf · doi:10.1039/c4fd00101j
published in Faraday Discussions 174, 37-56 (Royal Society of Chemistry)
openalex publication_date 2014/05/27 · arxiv created 2015/09/18 · arxiv updated 2015/09/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The accurate determination of the lowest electron attachment (EA) and ionization (IP) energies for molecules embedded in molecular junctions is important for correctly estimating, for example, the magnitude of the currents (I) or the biases (V) where an I-V curve exhibits significant non-Ohmic behavior. Benchmark calculations for the lowest electron attachment and ionization energies of several typical molecules utilized to fabricate single-molecule junctions characterized by n-type conduction (4,4'-bipyridine, 1,4-dicyanobenzene and 4,4'-dicyano-1,1'-biphenyl) and p-type conduction (benzenedithiol, biphenyldithiol, hexanemonothiol and hexanedithiol) based on the EOM-CCSD (equation-of-motion coupled-cluster singles and doubles) state-of-the-art method of quantum chemistry are presented. They indicate significant differences from the results obtained within current approaches to molecular transport. The present study emphasizes that, in addition to a reliable quantum chemical method, basis sets much better than the ubiquitous double-zeta set employed for transport calculations are needed. The latter is a particularly critical issue for correctly determining EAs, which is impossible without including sufficient diffuse basis functions. The spatial distribution of the dominant molecular orbitals (MOs) is another important issue, on which the present study draws attention, because it sensitively affects the MO energy shifts Φ due to image charges formed in electrodes. The present results cannot substantiate the common assumption of a point-like MO midway between electrodes, which substantially affects the actual Φ-values.