@article{Awoga_Oladunjoye_A._Evaluation_2012,
author={Awoga, Oladunjoye A. and Ikot, Akpan A. and Ituen, Eno E. and Akpabio, Louis E.},
howpublished={online},
year={2012},
abstract={We consider a four-level system with two subsystems coupled by weak
interaction. The system is in thermal equilibrium. The thermodynamics of
the system, namely internal energy, free energy, entropy and heat
capacity, are evaluated using the canonical density matrix by two methods.
First by Kronecker product method and later by treating the subsystems
separately and then adding the evaluated thermodynamic properties of each
subsystem. It is discovered that both methods yield the same result, the
results obey the laws of thermodynamics and are the same as earlier
obtained results. The results also show that each level of the subsystems
introduces a new degree of freedom and increases the entropy of the entire
system. We also found that the four-level system predicts a linear
relationship between heat capacity and temperature at very low
temperatures just as in metals. Our numerical results show the same trend.},
type={ArtykuĹ‚y / Articles},
title={Evaluation of the thermodynamics of a four level system using canonical density matrix method},
number={No 4 December},
pages={91-108},
journal={Archives of Thermodynamics},
publisher={The Committee on Thermodynamics and Combustion of the Polish Academy of Sciences},
doi={10.2478/v10173-012-0029-5},
keywords={Canonical density matrix, Kronecker product, Reduced density matrix, Entropy},
}