what is the rules of applying bias voltages b

[A.G]

Hello every one
I'm using vnl to calculate current of diblock molecular diode in which there is an accepting and donor part then i adjust that molecule between two gold electrode . I used to apply the positive and the negative bias to the left electrode and set the value of the right one as zero. Should i apply the positive bias to the right electrode and the negative bias to the left one? Or they are the same ? Or this is depends on which electrode (left or right) connected to the donor and which one connected to the acceptor part of the molecule? .......plz help me in that
 Thank you......

[Umberto Martinez]

The current is independent of how the voltages are applied, it only depends on their difference.
Also check the reference manual for more details: http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.transmissionspectrum.html