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Bulk transport system Date: 2015/07/06 04:52 Name: Khalid   <kimu206@gmail.com> Dear researchers, I appologize for asking this questions, as this is mostly related to the theory than the code. (1) I want to calculate the bulk transmission of a certain material, that is the contacts are made of the same material. I have seen an example given in the work directory, Lead-Graphene.dat and NEGF-Graphene.dat. In this case both contacts are made of graphene. I was wondering, in this case what should be the length of the channel? As the contacts are made of the same material, are not they be considered as a part of the channel? (2) Also I have seen that openmx can compute bulk transport [Periodic system under zero bias], by setting NEGF.Output.for.TranMain on. Now I was wondering: (a) can I obtain the current by integrating the transmission function obtained by this procedure? (b) what should be the difference between the results obtained by this two method (one with periodic system under zero bias and one with lead-contact-lead) (c) in the Periodic system under zero bias, can I apply gate voltage? I hope you would be kind to answer the questions. Thanks in advance. Khalid

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Re: Bulk transport system ( No.1 ) Date: 2015/07/06 19:07 Name: Artem Pulkin 1) In OpenMX the width of the channel is defined by the central section plus both leads. Of course the scattering region should contain some portion of leads (i.e. several unit cells), such that your final results (transmission) do not change upon adding more atoms to both sides of your channel. 2) a. yes; b. the results should be different; c. no Artem Re: Bulk transport system ( No.2 ) Date: 2015/07/06 19:45 Name: Khalid  <kimu206@gmail.com> Dear Sir, Thank you very much for your reply, but please ask me another thing. If I want to calculate the bulk transport with zero bias, can I apply an electric field from z direction by the key-word: scf. Electric.Field 0 0 1 ? I mean is there any theoretical conflict using this command in bulk transmission case? Thanks in advance Khalid Re: Bulk transport system ( No.3 ) Date: 2015/07/06 20:24 Name: Artem Pulkin I do not see any conflict for having transverse electric field. But it looks like it is not implemented in openmx. The only option so far is an empirical gate voltage through 'NEGF.gate.voltage'. Artem Re: Bulk transport system ( No.4 ) Date: 2015/07/07 02:51 Name: Khalid  <kimu206@gmail.com> Dear Sir, Thank you very much for your kind reply Khalid

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