Parameter dependences of the degree of polarization of the thermal emission from amorphous silicate dust as a function of frequency. For reference, the polarization degree with the same parameter set is shown by a solid line in each panel. The fraction of the atoms trapped in the TLS is set to be 0.01. In each panel, one of the variables characterizing the amorphous silicate dust is varied with respect to the reference model to see how the shape of the polarization degree responds to each variable. In the case of |$\Delta _0^\mathrm{max}/h = 100\:$|GHz shown in panel (a), |$\langle C_\nu ^\mathrm{pol}\rangle$| defined by equation (21) takes negative values between 100 and 500 GHz. The polarization cross-sections take positive values for all other cases shown in these figures. The variables are (a) |$\Delta _0^\mathrm{max}$|⁠, expressed in the corresponding frequency normalized by |$h$|⁠, (b) |$R_{\Delta }$|⁠, (c) |$T$|⁠, (d) |$\tau _+$|⁠, and (e) |$L_\mathrm{min}$|⁠, respectively. The given values for each parameter are shown in the legends.