Fig. 7. Results of model calculations.

a Pressure dependence of the anisotropy parameter D/k_B. b Pressure dependence of the exchange coupling parameter J_c/k_B. c Pressure dependence of the transverse exchange coupling parameter J_a/k_B. The calculation results are shown for the pressures, matching the experiments. d The Sakai–Takahashi phase diagram for a quasi-1D spin-1 antiferromagnet⁴⁴. The red open points correspond to QMC calculations for the phase boundary⁴⁵; the red line is a prediction based on the ansatz as described in the text. The purple circles correspond to estimates of the spin Hamiltonian parameters at given pressures. The dotted cross marks the critical parameter values at 4.2 kbar.