Jm. Wesselinowa et al., THE GREENS-FUNCTION TECHNIQUE FOR SPIN-PHONON INTERACTIONS IN SQUARICACID, Journal of physics. Condensed matter, 7(8), 1995, pp. 1701-1709
A Green's function technique is used to study the effects of spin-phon
on interactions in squaric acid including higher-order anharmonic term
s. The renormalized energy and the damping of the spin waves and the p
honons have been evaluated for the first time. The anharmonicity effec
ts play an important role in the vicinity of T-c and above T-c.