In principle, the AdSoS scheme does not introduce any non-conservativeness per se, so that it should by default sample a microcanonical (NVE) ensemble in the absence of a thermostat. In practice, however, the use of finite values for the integration timestep and for the non-bonded cutoff will lead to energy drifts. These are removed by the thermostat in the canonical (NVT) ensemble, and one could easily imagine a variant using an "ergostat" (i.e. a heat exchange designed to maintain the total energy of the system) that would sample the microcanonical one.