Comment on 'Thermal entangled quantum Otto engine based on the two qubits Heisenberg model with Dzyaloshinskii-Moriya interaction in an external magnetic field'

Abstract

In the paper Hao Wang et al (2012 Phys. Scr. 86 015001) have studied the entangled quantum Otto engine and have derived some thermodynamics quantities like the amount of heat energy exchange, the net work output and the efficiency. Our investigations reveal that although the numeric results (figures) are correct, but the analytic formulas for heat, work, and efficiency are not correct.