Figure 2

Dependence of SMO energy on tilting angle and in-plane constraint.

(a) Dependence of total free energy per formula unit on tilting angle and in-plane lattice constant for tilting modes of c⁺, c⁻, a⁺ and a⁻. (b) Minimum total free energy per formula unit as a function of in-plane lattice constant for different tilting modes with the no-tilting case marked by the solid line. (c) Partial enlarged view of the energy curve around the lattice constant of 3.78 Å and 3.83 Å. (d) Dependence of the tilting angle of minimum energy on in-plane lattice constant. (e) Relative change of the two valleys on the energy curve of a⁻ tilting with the change of the in-plane lattice constant.