Dear Nascimento, first of all, for the transport calculation, try to enhance a bit the electrode layer and check again the results.
For the stress, I would recommend.... Create an initial guess for the ribbon with a slightly bigger carbon-carbon bond for all the atoms. Then relax the whole structure in siesta but fix the positions of the atoms located on the extremeties (along the uniaxial direction). And do this enhancement gradually... Then you would have an strained structure... best regards CGRocha On 6 January 2012 15:22, Clerisson Nascimento <[email protected]> wrote: > Dear all, > > I'm interested in transport properties of graphene nanoribbon under > uniaxial strain. I have read some posts here on list so i got some > direction. But i'm still a little bit confused regarding a couple things. > > First, i made one unit cell of an AGNR8 then relax that using > MD.VariableCel=T in order to get the new coordinates, new lattice vectors, > stress tensor near of zero and for to fit the gap with the outcome in these > papers. Then i get a scattering region containing 7 unit cells (1 for elec + > 5 for scattering region + 1 for elec ), relax that using the same way that i > made with electrodes in order to get the new lattice vectors and the new > corrdinates of the scattering region with epsilon=0. But even i get a right > value of gap on the electrodes, the current value do not fits with the > papers results. I'm wondering if i'm doing the right way. > > My second question is regarding to "apply " the stress on the system. In > practical, how can i do that on siesta/transiesta? In the papers, and here > on list, it's said that first you should get the relaxed structure > (epsilon=0) then modify the lattice vector to the calculated value. My > question is the following, should i modify the value in "%block > LatticeVectors" or should i made an new nanoribbon using new value for the > lattice constant? > > I would be appreciated if could someone give me some direction on my > problem. > > Thaks in advance and a happy new yer to all. > Clerisson Nascimento.
