Fig. 5: Thermal expansion.
The order of the thermal expansion for the five polymorphs predicted by (a) soapGAP: β < α ≃ κ ≃ γ < δ; and (b) tabGAP: β ≃ γ < κ < δ < α. The order predicted by the soapGAP agrees well with the first-principles calculations in ref. 61 (the four dotted lines for β/κ/α/δ in panel (a) with the same colors as the soapGAP ones). The main differences between the soapGAP and tabGAP are the α-phase and γ-phase. The error bars represent the standard deviations caused by temperature/pressure fluctuation.
