506 research outputs found
All-electron GW calculation for molecules: Ionization energy and electron affinity of conjugated molecules
An efficient all-electron GW method and a quasiparticle
selfconsistent GW (QSGW) method for molecules are proposed in the molecular
orbital space with the full random phase approximation. The convergence with
basis set is examined. As an application, the ionization energy () and
electron affinity () of a series of conjugated molecules (up to 32 atoms)
are calculated and compared to experiment. The QSGW result improves the
GW result and both of them are in significantly better agreement with
experimental data than those from Hartree-Fock (HF) and hybrid density
functional calculations, especially for . The nearly correct energy gap and
suppressed self-interaction error by the HF exchange make our method a good
candidate for investigating electronic and transport properties of molecular
systems.Comment: 4 pages, 2 figures, 1 tabl
Time-Dependent Transport Through Molecular Junctions
We investigate transport properties of molecular junctions under two types of
bias--a short time pulse or an AC bias--by combining a solution for the Green
functions in the time domain with electronic structure information coming from
ab initio density functional calculations. We find that the short time response
depends on lead structure, bias voltage, and barrier heights both at the
molecule-lead contacts and within molecules. Under a low frequency AC bias, the
electron flow either tracks or leads the bias signal (capacitive or resistive
response) depending on whether the junction is perfectly conducting or not. For
high frequency, the current lags the bias signal due to the kinetic inductance.
The transition frequency is an intrinsic property of the junctions.Comment: 5 pages, 9 figure
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