title: Edge reconstruction in armchair phosphorene nanoribbons revealed by discontinuous Galerkin density functional theory.
abstract: With the help of our recently developed massively parallel DGDFT (Discontinuous Galerkin Density Functional Theory) methodology, we perform large-scale Kohn-Sham density functional theory calculations on phosphorene nanoribbons with armchair edges (ACPNRs) containing a few thousands to ten thousand atoms. The use of DGDFT allows us to systematically achieve a conventional plane wave basis set type of accuracy, but with a much smaller number (about 15) of adaptive local basis (ALB) functions per atom for this system. The relatively small number of degrees of freedom required to represent the Kohn-Sham Hamiltonian, together with the use of the pole expansion the selected inversion (PEXSI) technique that circumvents the need to diagonalize the Hamiltonian, results in a highly efficient and scalable computational scheme for analyzing the electronic structures of ACPNRs as well as their dynamics. The total wall clock time for calculating the electronic structures of large-scale ACPNRs containing 1080-10,800 atoms is only 10-25 s per self-consistent field (SCF) iteration, with accuracy fully comparable to that obtained from conventional planewave DFT calculations. For the ACPNR system, we observe that the DGDFT methodology can scale to 5000-50,000 processors. We use DGDFT based ab initio molecular dynamics (AIMD) calculations to study the thermodynamic stability of ACPNRs. Our calculations reveal that a 2 × 1 edge reconstruction appears in ACPNRs at room temperature.
authors.affiliation: Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. whu@lbl.gov linlin@math.berkeley.edu cyang@lbl.gov.
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.affiliation: Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. whu@lbl.gov linlin@math.berkeley.edu cyang@lbl.gov and Department of Mathematics, University of California, Berkeley, CA 94720, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.affiliation: Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. whu@lbl.gov linlin@math.berkeley.edu cyang@lbl.gov.
authors.forename: Chao
authors.initials: C
authors.lastname: Yang