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General Questions and Answers / Re: Can I run this command using VNL?
« on: June 22, 2017, 15:58 »
There is no bias voltage applied in this calculation. However, the Hartree Difference Potential (HDP) does not need to be the same in the left and right electrodes at zero bias. The definition of the HDP is discussed in Notes at http://docs.quantumwise.com/manuals/Types/HartreeDifferencePotential/HartreeDifferencePotential.html.
The second figure shows the same HDP that has been averaged along the Z-direction to smoothen the oscillation related to the discrete nature of atoms. The plot is rigidly shifted as you have noticed, but as any electrostatic potential the HDP is defined up to a constant. So, it is equally good for describing band bending in Si discussed in the tutorial, and was set to zero in the right electrode to align the averaged HDP with the Fermi level in the doped Si (comprising the right electrode) as shown in the PLDOS figure.
The second figure shows the same HDP that has been averaged along the Z-direction to smoothen the oscillation related to the discrete nature of atoms. The plot is rigidly shifted as you have noticed, but as any electrostatic potential the HDP is defined up to a constant. So, it is equally good for describing band bending in Si discussed in the tutorial, and was set to zero in the right electrode to align the averaged HDP with the Fermi level in the doped Si (comprising the right electrode) as shown in the PLDOS figure.