Let me add that your current simulation does not advocate using k-point sampling transverse to the transport direction.
1. Why do you have no transverse periodicity? Also, your converged scattering region is "missing" more than 1 electron. This tells me that your system is ill-setup, either from a geometrical point of view, or from a calculation parameter point of view. 2. Check your convergence parameters. I would say your lower energy bound is too high. You should probably go to -30 eV or even lower. 2016-05-23 12:21 GMT+02:00 Aaron <[email protected]>: > Hi Raha, > > It can be slightly difficult to compare between methods. Are you ensuring > that the basis set size is the same between DFTB and DFT methods for > example? > > I can suggest either tightening convergence criteria or else increasing > number of k points. (In the paper linked they used a 4x4 k point grid > whereas you use gamma point). Averaging over multiple k points would help > to smear out the spikes. > > Regards, > Aaron > > > On 22/05/16 13:41, Raha khalili wrote: > > > Dear Nick and Aaron, > > Many thanks for your reply. Yes, my calculations has converged as you can > see in my attached output files. > > On Sun, May 22, 2016 at 1:34 AM, Thong, Aaron <[email protected]> > wrote: > >> Hi Raha, >> >> How do you define what is correct for your transmission? Are you trying >> to reproduce a certain literature result? >> > > I am trying to do some calculations on amine-linked single molecular > junctions with DFTB and I need to compare my results to DFT (the results > from DFTB are attached). My DFTB transmission is smoother than DFT one and > I can not compare these two calculations. There also is a DFT calculation > on a same structure in "PHYSICAL REVIEW B 83, 115108 (2011)" that differs > from my calculations. > > I'm not sure if my Transiesta calculations is correct or not. As first, I > optimized the attached molecule to electrodes by siesta, then used the > optimized structure in my Transiesta calculation. > > Regards, > Raha > > >> >> >> Spike peaks in transmission is quite common for single molecule junctions >> since the Dos of these junctions would be spikes. >> >> Regards >> Aaron >> >> >> >> Sent from my Samsung device >> >> >> -------- Original message -------- >> From: Raha khalili <[email protected]> >> Date: 21/05/2016 9:35 pm (GMT+00:00) >> To: [email protected] >> Subject: [SIESTA-L] Transmission problem >> >> Dear All, >> >> I am trying to find the transmission of a single molecule junction by >> using Transiesta but the final result doesn't seem to be correct with many >> spike-like peaks. >> >> Here are attached my input files and final T results. >> Any help will be really appreciated. >> >> kind regards, >> Raha >> >> >> -- >> Khadijeh Khalili >> Nanotechnology group, Physics department, university of Mazandaran >> Babolsar, Iran >> > > > > -- > Khadijeh Khalili > Nanotechnology group, Physics department, university of Mazandaran > Babolsar, Iran > > > -- > PhD student > B321/28 > Aaron Thong > > -- Kind regards Nick
