QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: kaypu on October 24, 2012, 13:51
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Dear QuantumWise staff:
i've read some paper about the effect of different electrode on the transport. For example: someone use Al for left electrode, and Au for right electrode.
for the different metal, their electrochemical potential is different, so, at the 0V, there may exists current. is that right? in atk, under 0V, there is no current, why ???
Regards
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A current corresponds to transfer of energy, but if you are not supplying any energy (via an applied bias) you cannot have a current flow. What happens at 0 V is that a dipole layer is formed in the middle which balances the difference in chemical potential out. The formation of this dipole layer is equivalent to a local current, in a transient sense, but the net final current will be zero. This is also clear from the formula, where you (in the zero-temperature limit) integrate from Ef-V/2 (Ef is the common Fermi level) to Ef+V/2 where V is the bias. If V=0 the integration interval is zero so the integral must be zero.
If you apply a different electron temperature to both sizes, you can get a current at zero bias, but then you are injecting energy into the system by keeping the reservoirs (the electrodes) at constant different temperatures.
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thank you professor Anders