Your electrodes may be erroneously setup. I encourage you to check the electronic structure (ES) of something you already know the result of. If you can't reproduce such an ES you may question your compilation.
2016-03-17 13:45 GMT+01:00 <[email protected]>: > Dear Rajan, > > thanks for this information. I will in future work with this procedure. > > Some more things that confuse me are the following: > > 1. When I re-run the same setup, I get deviations up to 15% in the > transmission. What could be the reason for this? > > 2. I did calculations of the same setup with transiesta 3.2-pl-5 and 4.0b-485 > and also got quite different characteristics in the transmission spectrum. > Same question: what could be the reason for this? I didn't notice any changed > defaults. > > Apart from this, are there reliable ways to tell if my compilation is stable? > > Thanks and best regards, > JH > > Rajan Singh schrieb am 2016-03-14: >> Hii > >> You should do following steps: > >> 1. Decide your structure >> 2. Run structure with different k pts and plot energy vs k pt >> See after some k pt energy values nearly same >> 3. Do same with mesh cuttoff >> 4. Relax structure with CG steps >> 5. Then electrode calculation >> And finally tranmission calculations > >> Regards >> Rajan Singh > >> Sent from my Sony Xperia™ smartphone > >> [email protected] wrote: > >> >Dear users, >> > >> >I am pretty new to Siesta/TranSiesta and I'm currently struggling with the >> >following topic: I want to compute equilibrium transmission of >> >Poly(3-Methylthiophene) with different chain lengths. My current (ideally >> >periodic) _test_ system consists of 100 atoms (a 10mer) of which 2x40 atoms >> >build the electrodes. At the moment I'm doing lots of tests with different >> >parameters like k vectors, box sizes, MeshCutoff and others. The finally >> >important quantity is the transmission. >> >My problem is now that I'm not really seeing a "pattern": I find it hard to >> >understand which physical quantity indicates a good or bad convergence >> >w.r.t. the transmission. I'm observing energies and of course the >> >transmission function. What confuses me most is that the transmission >> >function changes shape very drastically for changes like e.g. increasing or >> >decreasing the kx,ky vectors by 1. Sometimes transmission values de- or >> >increase by up to 6 magnitues, in combination with a totally different >> >characteristic. >> >Also, the same calculation yields deviations of up to 15% at for example >> >T(E=Ef) when repeated. Could this be connected to a numerical instability >> >due to a compilation problem or a "defective" math library? >> >Literature indicates a transmission T(E=Ef) ~ 0-1 G0. Most of my results >> >range between 0.17 and 0.01 G0 (again: with very different transmission >> >function shapes). >> >I'm afraid of having an understanding problem somewhere or missing out >> >something important. >> > >> >I hope that I can get some advice. >> > >> >Thanks and best regards, >> >JH -- Kind regards Nick
