#!/bin/sh # In the wide-band limit (WBL) the coupling to the leads is assumed to be independent of energy. # Therefore one does not need to calculate any self-energies. # This also means that the eigenspace of the Green's function is independent of energy. # It can therefore be diagonalized in advance, # greatly speeding up the calculation of the DOS and the transmission. # In the example $AMSHOME/examples/adf/green_Al/green_WBL.run of green, # the transmission of benzenedithiol junction, example green_BDT.run, # in the wide-band limit (WBL) is calculated. # In order to model the molecule-metal interface, we do need to include a few gold layers # in the calculation. # However, unlike in green_Au.run, only a single atomic layer as the principal layer is used. # In green_BDT.run 3 layers of gold atoms from 1 fragment. # In this example green_WBL.run each layer of gold atoms has its own fragment. # Because a single atomic layer is an unnatural configuration for gold, # a minor amount of smearing is necessary to make the calculation converge. # The molecule is sandwiched in between the electrodes just like before # (see the example for benzenedithiol, example green_BDT.run). # However, this time each atomic layer of gold gets its own fragment. # The reason for this configuration is that if the WBL is used on the # entire gold contact the result is an an unphysical coupling to the leads; # even the gold atoms contacting the molecule would have a direct coupling to the environment. # A much better result can be obtained by only using the WBL on the back-most atomic layer # and letting the electrons propagate naturally through the rest of the contact. # Because the WBL is computationally so inexpensive, we can easily calculate # the DOS and transmission for 10,000 points instead of 1000. cp $AMSHOME/examples/adf/green_Al/Au.5p . cp $AMSHOME/examples/adf/green_Al/Au.5p.dirac . $AMSBIN/dirac < Au.5p.dirac mv TAPE12 t12.rel AMS_JOBNAME=Au $AMSBIN/ams <