N2 - 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.
JO - Archives of Thermodynamics
L1 - http://so.czasopisma.pan.pl/Content/94377/PDF/05_paper.pdf
L2 - http://so.czasopisma.pan.pl/Content/94377
IS - No 4 December
EP - 108
KW - Canonical density matrix
KW - Kronecker product
KW - Reduced density matrix
KW - Entropy
ER -
A1 - Awoga, Oladunjoye A.
A1 - Ikot, Akpan A.
A1 - Ituen, Eno E.
A1 - Akpabio, Louis E.
PB - The Committee on Thermodynamics and Combustion of the Polish Academy of Sciences
JF - Archives of Thermodynamics
SP - 91
T1 - Evaluation of the thermodynamics of a four level system using canonical density matrix method
UR - http://so.czasopisma.pan.pl/dlibra/docmetadata?id=94377
DOI - 10.2478/v10173-012-0029-5