Calculating phase-coherent quantum transport in nanoelectronics with ab initio quasiatomic orbital basis set
We present an efficient and accurate computational approach to study phase-coherent quantum transport in molecular and nanoscale electronics. We formulate a Green’s-function method in the recently developed ab initio nonorthogonal quasiatomic orbital basis set within the Landauer-Büttiker formalis...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2011
|
| Online Access: | http://hdl.handle.net/1721.1/64475 https://orcid.org/0000-0002-2727-0137 |
| Summary: | We present an efficient and accurate computational approach to study phase-coherent quantum transport in
molecular and nanoscale electronics. We formulate a Green’s-function method in the recently developed ab
initio nonorthogonal quasiatomic orbital basis set within the Landauer-Büttiker formalism. These quasiatomic
orbitals are efficiently and robustly transformed from Kohn-Sham eigenwave functions subject to the maximal
atomic-orbital similarity measure. With this minimal basis set, we can easily calculate electrical conductance
using Green’s-function method while keeping accuracy at the level of plane-wave density-functional theory.
Our approach is validated in three studies of two-terminal electronic devices, in which projected density of
states and conductance eigenchannel are employed to help understand microscopic mechanism of quantum
transport. We first apply our approach to a seven-carbon atomic chain sandwiched between two finite crosssectioned
Al 001 surfaces. The emergence of gaps in the conductance curve originates from the selection rule
with vanishing overlap between symmetry-incompatible conductance eigenchannels in leads and conductor. In
the second application, a 4,4 single-wall carbon nanotube with a substitutional silicon impurity is investigated.
The complete suppression of transmission at 0.6 eV in one of the two conductance eigenchannels is
attributed to the Fano antiresonance when the localized silicon impurity state couples with the continuum states
of carbon nanotube. Finally, a benzene-1,4-dithiolate molecule attached to two Au 111 surfaces is considered.
Combining fragment molecular orbital analysis and conductance eigenchannel analysis, we demonstrate that
conductance peaks near the Fermi level result from resonant tunneling through molecular orbitals of benzene-
1,4-dithiolate molecule. In general, our conductance curves agree very well with previous results obtained
using localized basis sets while slight difference is observed near the Fermi level and conductance edges. |
|---|