PtH2Pt nanojunction: Difference between revisions
From phys824
Jump to navigationJump to search
Line 8: | Line 8: | ||
==NEGF+DFT modeling of electronic transport== | ==NEGF+DFT modeling of electronic transport== | ||
*Calculate zero-bias transmission function: | *Calculate zero-bias transmission function using pth2pt_lcao.py script: | ||
<pre> | <pre> | ||
Line 76: | Line 76: | ||
# could have 3rd argument specified the nth point of V to begin wiht | # could have 3rd argument specified the nth point of V to begin wiht | ||
t.calculate_iv() # for zero-bias transmission, don't put argument. | t.calculate_iv() # for zero-bias transmission, don't put argument. | ||
</pre> | |||
*Plot zero-bias transmission function: | |||
<pre> | |||
</pre> | </pre> |
Revision as of 08:59, 1 December 2014
Experimental Motivation
- R. H. M. Smit, Y. Noat, C. Untiedt, N. D. Lang, M. C. van Hemert and J. M. van Ruitenbeek, Measurement of the conductance of a hydrogen molecule, Nature 419, 906 (2002). [PDF]
- M. Kiguchi, R. Stadler, I. S. Kristensen, D. Djukic, and J. M. van Ruitenbeek, Evidence for a single hydrogen molecule connected by an atomic chain, Phys. Rev. Lett. 98, 146802 (2007). [PDF]
NEGF+Tight-Binding modeling of electronic transport
NEGF+DFT modeling of electronic transport
- Calculate zero-bias transmission function using pth2pt_lcao.py script:
""" Transport calculations using transport object following https://wiki.fysik.dtu.dk/gpaw/documentation/transport/negftransport.html """ from ase import Atoms from gpaw.transport.calculator import Transport from gpaw.atom.basis import BasisMaker from gpaw.occupations import FermiDirac from gpaw.poisson import PoissonSolver from gpaw.mixer import Mixer from ase.visualize import view a = 2.41 # Pt binding lenght b = 0.90 # H2 binding lenght c = 1.70 # Pt-H binding lenght L = 7.00 # width of unit cell # L-Lead scat region R-Lead #------------ ------------------- ----------- # Pt--Pt--Pt-|-Pt--Pt-H-H-Pt--Pt-|-Pt--Pt--Pt # 0 1 2 3 4 5 6 7 8 9 10 11 #------------ ------------------- ----------- atoms = Atoms('Pt5H2Pt5', pbc=( 0, 0,1), cell=[ L, L, 9 * a + b + 2 * c]) atoms.positions[:5, 2] = [i * a for i in range(5)] atoms.positions[-5:, 2] = [i * a + b + 2 * c for i in range(4, 9)] atoms.positions[5:7, 2] = [4 * a + c, 4 * a + c + b] atoms.positions[:, 0:1] = L / 2. atoms.center() # setup leads pl_atoms1 = range(3) # 3 atoms 0~2 is L-Lead pl_atoms2 = range(9,12) # 3 atoms 9~11 is R-Lead pl_cell1 = (L, L, 3 * a) # cell size of lead 3 Pt bonds pl_cell2 = pl_cell1 # visulize device with ag view(atoms) t = Transport(h=0.3, xc='PBE', basis='szp(dzp)', kpts=(1,1,1), # occupations=FermiDirac(0.1), mode='lcao', poissonsolver=PoissonSolver(nn=2, relax='GS'), txt='ptH2_lcao.txt', mixer=Mixer(0.1, 5, weight=100.0), pl_atoms=[pl_atoms1, pl_atoms2], pl_cells=[pl_cell1, pl_cell2], pl_kpts=(1,1,10), # lead is periodic along transport direction plot_energy_range = [-4.,4.], # min and max energy of transmission plot_energy_point_num = 201, # Number of energy points #edge_atoms=[[0, 2], [0, 5]], # edge and mol_atoms should be #mol_atoms=range(1,5), # specified to be able to restart. #analysis_mode=True, # for restarting jobs #scat_restart=True, # need to specify mol_atom #lead_restart=True, #guess_steps=1, non_sc=True, #True = Normal DFT (default)for zero bias transmission, False = NEGF-DFT ) atoms.set_calculator(t) #t.calculate_iv(0.5, 3) # for finite-bias cal, 0~0.5 eV, 3 steps ,return V=0,0.25 and 0.5 in this case. # could have 3rd argument specified the nth point of V to begin wiht t.calculate_iv() # for zero-bias transmission, don't put argument.
- Plot zero-bias transmission function: