negative transmission coefficiencies of monolayer MoS2 FET

[beauyy]

Dear sir,
 I calculated the gatescan curves of monolayer MoS2 FET. At the V_g = -1.0 V and 0.5 V and V_D = 0 V, many values of transmission coefficiencies are negative， especially near E = 0 eV. The monolayer MoS2 is optimized until the max force is less 0.1 eV/A. Resursion is used to tackle with the self-energy calculation and transmission.
Would you please tell me what is the problem with the negative transmission coefficiencies? The attached files are the detailed transmission coefficiencies of monolayer MoS2 at V_g = 0.5 V and V_D = 0 V and the optimized MoS2 device.
Should the device be re-optimized after the dielectric layer and metallic layer is added on the MoS2?

[Anders Blom]

Probably you used Krylov self-energy method? Anyway, negative values of 1e-11 has no influence on the current anyway, but switch to Recursion to avoid negative values in general.

[beauyy]

Probably you used Krylov self-energy method? Anyway, negative values of 1e-11 has no influence on the current anyway, but switch to Recursion to avoid negative values in general.

Sir,
  I am sure that I have used Recursion to calculate the self-energy and there is no negative transmission coefficiencies at V_g = 0. But when gate voltage is applied, the negative transmission coefficiencies occur, some are larger than 1e-5. I am afraid that such values can not be neglected.

[Anders Blom]

What ATK version?

[beauyy]

11.8.2
It seems that I have found the reason for the negative transmission. The transmission is calculated without SCF iteration. Thanks very much for your helpful suggestions