QuantumATK Forum

QuantumATK => Scripts, Tutorials and Applications => Topic started by: canyesil on March 14, 2016, 09:32

Title: How to calculate valley resolved transmission in graphene
Post by: canyesil on March 14, 2016, 09:32
1) In graphene, application of strain must cause a gauge potential that has opposite sign for K and K' valleys. Therefore, in the case of strained region on graphene, valleys must deflect to transverse directions. This also reduces the conductance at some energy levels. Is there a way to calculate the transmission of K and K' independently?

2) In the VNL buildder, I am using ''stretch the cell'' to apply uniaxial strain. In that case, does the calculation consider a gauge potential that affects kx and ky in the Hamiltonian. For example, if the strain is uniaxial along transport direction of armchair graphene, this only generate a gauge potential on ky. So electrons must deflect (similar with application of magnetic field). Due to some reflection, conductance must decrease. Is the system considering this approach?

Example works:

Applied Physics Letters 97,043508 (2010)
Applied Physics Express 8,105201 (2015)
AIP Advances 6, 056303 (2016)
Title: Re: How to calculate valley resolved transmission in graphene
Post by: Jess Wellendorff on March 14, 2016, 09:43
1) You can easily calculatr the transmission in whatever k-point you like. Just specify the kpoint(s) as a list in the options for TransmissionSpectrum: http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.transmissionspectrum.html (http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.transmissionspectrum.html)

2) No, ATK does not impose such system-specific constraints on the calculation. The calculation is done completely ab initio,  and will capture the effects you describe as well as the selected level of theory is able to (e.g. DFT).