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Ghost transmission: How large basis sets can make electron transport calculations worse
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10.1063/1.3283062
/content/aip/journal/jcp/132/2/10.1063/1.3283062
http://aip.metastore.ingenta.com/content/aip/journal/jcp/132/2/10.1063/1.3283062

Figures

Image of FIG. 1.
FIG. 1.

(a) Partitioning of the full electrode-molecule-electrode system as employed in a finite cluster approach. Two alternative definitions of the central system are shown, one that only comprises the molecule , and one that comprises the molecule and several electrode atoms . (b) Definition of the central subsystem Hamiltonian and the coupling matrices as submatrices of the full one-particle Hamiltonian.

Image of FIG. 2.
FIG. 2.

Schematic illustration of the ghost basis setup for a model junction consisting of a Au–H–H–H–H–Au chain, where the central region is defined as the four H atoms. While a full calculation (left) contains both the basis functions (for simplicity, only one function per atom is shown, denoted by the blue lobes) and the atomic nuclei with all electrons associated with the neutral atoms (denoted by golden and red circles), the ghost calculation (right) has the atomic nuclei and the electrons removed in the central region.

Image of FIG. 3.
FIG. 3.

Transmission for (a) octanedithiolate chains in two different conformations and (b) their silane analogs using clusters to mimic the coupling to gold electrodes. The LANL2DZ ghost transmission is in all cases too low to be displayed. KS-DFT(BP86); various Gaussian-type atom-centered basis sets. Electronic structure program: QCHEM.

Image of FIG. 4.
FIG. 4.

Ball-and-stick model of the model junction.

Image of FIG. 5.
FIG. 5.

Transmission for the model junction using (a) different exponents for the four -type Gaussian basis functions and (b) different combinations of matrix blocks. and refer to exponents of (diffuse) and (local), respectively. See Fig. 1 for definitions of the matrix blocks. KS-DFT—BP86/TZVP(Au), -type ghost basis function (H).

Image of FIG. 6.
FIG. 6.

Isosurface plots of the central subsystem MOs of the model junction (see Appendix B for a definition of subsystem MOs).

Image of FIG. 7.
FIG. 7.

Transmission for the meta-connected benzene derivatives using clusters to mimic the coupling to gold electrodes. KS-DFT(BP86); various Gaussian-type atom-centered basis sets. Electronic structure program: QCHEM.

Image of FIG. 8.
FIG. 8.

Influence of the EM size on transmission functions for (a) para- and (b) meta-connected benzene derivatives using clusters to mimic the coupling to gold electrodes. KS-DFT(BP86), TZVP. Electronic structure program: QCHEM.

Image of FIG. 9.
FIG. 9.

Influence of the EM size on the transmission functions for (a) para- and (b) meta-connected benzene derivatives using clusters to mimic the coupling to gold electrode. KS-DFT(BP86) in combination with the scalar-relativistic ZORA approximation; small frozen cores; TZ2P basis set (DZ for comparison). Electronic structure program: ADF.

Image of FIG. 10.
FIG. 10.

Influence of the EM size and the LDOS value on transmission functions for (a) para- and (b) meta-connected benzene derivatives using clusters to mimic the coupling to gold electrodes. The values in the legend refer to the constant LDOS in Eq. (6). KS-DFT(BP86), TZVP. Electronic structure program: QCHEM.

Tables

Generic image for table
Table I.

Central subsystem Fock matrix for the small-exponent (“D”) and the large-exponent (“L”) calculations. Entries are given in eV.

Generic image for table
Table II.

and at for the individual eigenvectors (MOs) of the central subsystem for the small-exponent (diffuse) and the large-exponent (local) calculations. Entries are given in eV.

Generic image for table
Table III.

Energies and couplings and at the Fermi energies for the individual eigenvectors (MOs) of the central subsystem. Energies are given in eV. The assignments HOMO and LUMO are given by similarities in shape with the corresponding MOs calculated for the isolated molecule.

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/content/aip/journal/jcp/132/2/10.1063/1.3283062
2010-01-12
2014-04-24
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Ghost transmission: How large basis sets can make electron transport calculations worse
http://aip.metastore.ingenta.com/content/aip/journal/jcp/132/2/10.1063/1.3283062
10.1063/1.3283062
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