Dear Jose A.:
Thank you very much again!
Sincerely,
Mengqiu
> From: jose.torres.alo...@uam.es
> To: siesta-l@uam.es
> Date: Thu, 17 Jun 2010 17:57:26 +0200
> Subject: RE: [SIESTA-L] Who can help me!
>
> Dear Mengqiu:
>
> Transiesta is designed to give accurate
> calculations of larger currents, it is designed
> for the contact regime (as opposed to the tunneling
> regime).
>
> So it is not supposed to be accurate in the tunneling
> regime because the description of the tunneling
> barrier itself is not accurate, and the numerical
> error is close to the values obtained
> for that case.
>
> You will certainly obtain some values for that
> tunneling configuration, but use them at your
> own risk!
>
> My suggestion is to change the configuration
> to try to make the tunneling regime as
> "little tunneling" as possible (currents of about
> 100 nA per atom or larger) and try to conclude
> the physics of the system from there.
>
> Yours
> Jose A.
>
> On Thu, 2010-06-17 at 15:08 +0000, CaiMeng-Qiu wrote:
> > Dear Jose A. Torres
> >
> > > In the examples you show probably the Kx,Ky mesh is
> > > not converged yet. (But it seems to me in any case
> > > that you are getting different expressions for a numerical
> > > "zero" for the current.)
> >
> > My system is tunneling junction with insulated barrier. Can the
> > Transiesta calculation distinguish the tiny current?
> >
> > Thank you again!
> >
> > Sincerely,
> >
> > Mengqiu
> >
> > >>
> > >
> > > On Thu, 2010-06-17 at 13:04 +0000, CaiMeng-Qiu wrote:
> > > > Dear Jose A. Torres：
> > > >
> > > > Thank you very much again!
> > > > I also several questions for these.
> > > >
> > > >
> > > > >
> > > > >
> > > > > On Thu, 2010-06-17 at 11:54 +0000, CaiMeng-Qiu wrote:
> > > > > > Dear Jose A. Torres：
> > > > > >
> > > > > > Thank you much for your explanation in detail.
> > > > > >
> > > > > > >
> > > > > > > - Also choose a large enough number of points to
> > > > > > > describe the function T(E) properly! (it may
> > > > > > > have sharp peaks)
> > > > > >
> > > > > > Do you mean I should adopt the dense k-mesh and large value of
> > > > > > TSTBT.NPoints?
> > > > >
> > > > > Here I just mean a TSTBT.NPoints to be large enough.> >
> > > >
> > > > In the TRANSIESTA-manual, it mentions:" In the case of tbtrans,
> > the
> > > > k-point sampling has to be specified also using a
> > kgrid_Monkhorst_Pack
> > > > block, and can differ from the sampling that was used in the
> > > > TRANSIESTA calculation. The convergence of the transmission
> > function
> > > > with respect to the k sampling can be slower than the one for the
> > > > density matrix. This means that one may have to increase the
> > number of
> > > > k-points used in tbtrans." Did it mean that we adopt the dense
> > k-mesh
> > > > for the tbtrans calcualtion after the Transiesta calculation?
> > > >
> > > > I do find that, for the special TSTBT.NPoints, the varied k-mesh
> > in
> > > > the xy-plane generate the changed current.
> > > > For examplefor the tbtrans calcultions:
> > > > v -1.0 eV
> > > > TSTBT.NPoints 1500
> > > > k-mesh 6x6x50
> > > > I=-3.17E-16
> > > >
> > > > where:
> > > > v -1.0 eV
> > > > TSTBT.NPoints 1500
> > > > k-mesh 6x6x70
> > > > I=-3.17E-16
> > > >
> > > > where:
> > > >
> > > > v -1.0 eV
> > > > TSTBT.NPoints 1500
> > > > k-mesh 7x7x60
> > > > I=-2.94E-16
> > > >
> > > > where:
> > > > v -1.0 eV
> > > > TSTBT.NPoints 1500
> > > > k-mesh 8x8x60
> > > > I=-3.59E-16
> > > >
> > > > If i should check both the k-mesh and TSTBT.NPoints for the
> > > > calculated current?
> > > >
> > > > Thank you in advance!
> > > >
> > > > Sincerely,
> > > >
> > > > Mengqiu
> > > >
> > > > >
> > > > > >
> > > > > > Generally, how much is it for the value of TS.TBT.NPoints?
> > > > >
> > > > > A few hundreds to a few thousand points.
> > > > >
> > > > > >
> > > > > > Thank you very much again!
> > > > > >
> > > > > > Sincerely,
> > > > > >
> > > > > > Mengqiu
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > > >
> > ______________________________________________________________________
> > > > 使用新一代 Windows Live Messenger 轻松交流和共享！ 立刻下载！
> > >
> > >
> >
> >
> >
> > ______________________________________________________________________
> > 搜索本应是彩色的,快来体验新一代搜索引擎-必应,精美图片每天换哦! 立即试
> > 用！
>
>
_________________________________________________________________
一张照片的自白――Windows Live照片的可爱视频介绍
http://windowslivesky.spaces.live.com/blog/cns!5892B6048E2498BD!889.entry
