On the efficient methods to solve multi-subband BTE in 1D gas systems: Decoupling approximations versus the accurate approach

For the deterministic MSBTE solver in 1D gas systems, efficient methods including the accurate approach, the decoupling of even-odd components of the distribution function (f
_e
-f
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decouple), and the decoupling of subband index and subband energy (RTA) have been implemented. For 3D MOSFET simulations, compared to the accurate approach, the f
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-f
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decouple approach helps to retain the accuracy of drain current calculation, and, at the same time, significantly reduce the turn-around-time as well as the memory usage. The hybrid scheme combining the decouple and the RTA approach is a good option to improve further the efficiency, while high accuracy of the drain current calculation is remained.