  Self-heating effects can significantly degrade the performance in nanoscale
devices. We investigate self-heating effects in such devices based on
two-dimensional materials using ab-initio techniques. A new algorithm was
developed to allow for efficient self-energy computations, achieving a
$\sim$500 times speedup. It is found that for the simple case of free-standing
MoS$_2$ without explicit metal leads, the self-heating effects do not result in
significant performance degradation.
