The source is 'PRL 99, 247211 (2007)', 'Magnetoelastic Coupling and Symmetry Breaking
in the Frustrated Antiferromagnet -NaMnO2'. The formulas are presented on the last page, page 4, of this paper.
Any response is kindly welcome.
According to the literature, when monoclinic crystal structure transforms to triclinic, the following formulaes, regarding their lattice parameters are valid:
a(T) = 1/2 a(M) - 1/2 b(M)
b(T) = 1/2 a(M) + 1/2 b(M)
c(T) = c(M)
Where T and M stand for Triclinic and Monoclinic, respectively...
Homework Statement
Consider three Ising spins located at the vertices of a triangular lattice, interacting antiferomagnetically with each other. The energy of an interacting spin pair is minimized when the spins are antiparaller. However, in this case, the energy cannot be minimized, since...