| A closed system of the equations for the local Bloch vectors and spin correlation functions is obtained by decomplexification of the Liouville-von Neumann equation for 4 magnetic particles with the exchange interaction, that takes place in an arbitrary time-dependent external magnetic field. The numerical analysis of the quantum thermodynamic variables is carried out depending on separable mixed initial state and the magnetic field modulation. In our model absorbed or made by system work arises due to displacement power levels by a magnetic field. It was numerically found, that under unitary dynamics the work production of one part of system is compensated by absorption of work produced by the other part. The work production by the subsystem is accompanied the entropy growth and vice-versa, the entropy becomes less with work absorption by the subsystem. Under unitary evolution local dynamics of power production by the subsystems in the finite environment is investigated. The research of the "spin gas" properties is necessary for the implementation of quantum thermodynamic cycles in spin systems. |
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