Assuming e=h=1, by definition, I = Integrate( TS*[f_Left(E,T)-f_Right(E,T)]dE); where f is the fermi dirac ditribution and f_Left = f(E-V/2) and f_Right = f(E+V/2) (or vise versa. I forget the exact sign. Choose the sign where positive V results in positive I). Now, there are two ways of getting G. One is just go by definition G = dI/dV => get a few voltage and current, and voila! The second way is the realize that
dI/dV = d(Integrate( TS*[f_Left(E,T)-f_Right(E,T)]dE))/dV ~　Integrate (TS* d[f_Left - f_Right]/dV) dE) ~ Integrate dE (TS* df/dE). Chih-Chien Wang Research Assistance Institute of Atomic and Molecular Science, Academia Sinica, Taipei, Taiwan [email protected] ----- Original Message ----- From: Jingxian Yu To: [email protected] Sent: Thursday, June 11, 2015 1:18 PM Subject: Re: [SIESTA-L] dI/dV Hi Sandeep, I don't know which version you are using. For Siesta 3.2, the second column in a * .AVTRANS file is T(E), namely transmission probability. Cheers! Jin On 11-Jun-15 2:36 PM, Sandeep Kumar wrote: I think u may get G directly from one of outfile with extension .AVTRANS's second column marked as Trans[G0]. On Tue, Jun 9, 2015 at 7:47 PM, toufik esssakhri <[email protected]> wrote: yes, i use tbtrans but the out file contains the value of current for each voltage bias my question is, G is directally calcutated and printed in one of ouput files or i should write a script to differenciate dI/dV. at 0 bias G=(e**2/h)T(E) -------------------------------------------------------------------------- From: [email protected] Date: Tue, 9 Jun 2015 09:11:23 -0500 To: [email protected] Subject: Re: [SIESTA-L] dI/dV You can use the tbtrans post processing code (http://departments.icmab.es/leem/siesta/Documentation/Manuals/siesta-3.1-manual/node103.html) Alex On Tue, Jun 9, 2015 at 3:29 AM, toufik esssakhri <[email protected]> wrote: Dear all, in many paper, we can see that we can present the conductance G=dI/dV my question is how to get G from Transiesta calculation at 0 bias and under finite bias voltage? best -- Alexander J. Pak Graduate Research Assistant - The Hwang Group Department of Chemical Engineering Cockrell School of Engineering The University of Texas at Austin 1 University Station, C0400 Austin, Texas 78712 CPE 4.422 | O: (512) 471-1839 M: (917) 637-0413 | [email protected] -- Sandeep Kumar Junior Research Fellow (Physics) Punjab Technical University email:[email protected]
