## 3 Model Validation and Results Analysis
### Large Spheroidal Particle Case  
To validate the calculation precision of the IIM T-Matrix method for particles with large sizes, light scattering by a large spheroid particle is simulated by the IIM T-Matrix method and EBCM, respectively, and the result is shown in Figure 5. In this simulation, the light wavelength is set as \(\lambda=0.6~{}\upmu\)m, the refractive index of the particle is taken to be m = \(1.60-0.0008\)i, and the length of the horizontal and rotational axes are set as \(a\) = 4.5 \(\upmu\)m and \(b\) = 6.0 \(\upmu\)m, respectively. The region between the inscribed and circumscribed spheres is divided into 50 layers along the radial direction.  
From the figures, it can be found that the scattering phase matrix obtained by the IIM T-Matrix model shows a high consistency with that obtained by EBCM, indicating that the IIM T-Matrix method can simulate the large non-spherical particle effectively. For F\({}_{11}\), the relative simulation errors are all less than 10% in the scattering angles ranging from 0\({}^{\circ}\) to 120\({}^{\circ}\). Though the simulation errors are slightly larger in the scattering angles in large scattering angles, its maximum error is smaller than 15%. For F\({}_{12}\)/F\({}_{11}\) and F\({}_{44}\)/F\({}_{11}\), the calculation errors of the IIM-T-matrix model are less than 0.05 in most scattering directions, especially in scattering angles ranging from 0\({}^{\circ}\) to 60\({}^{\circ}\), the modeling accuracy is much higher than other scattering directions. The simulation accuracy of F\({}_{34}\)/F\({}_{11}\) is slightly lower than that of F\({}_{12}\)/F\({}_{11}\) and F\({}_{44}\)/F\({}_{11}\), but their simulation errors are still less than 0.1 at most scattering angles. Similar to the small spheroidal particle, the simulation accuracy is lower in the large scattering angles, while in the forward scattering directions, the simulation errors are much smaller.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Model Type** & \(\mathbf{C_{ext}/\upmu m^{2}}\) & \(\mathbf{C_{abs}/\upmu m^{2}}\) & \(\mathbf{C_{sca}/\upmu m^{2}}\) & \(\mathbf{\omega}\) \\ \hline EBCM & 4.889 & 0.0953 & 4.793 & 0.98036 \\ IIM T-Matrix & 4.872 & 0.0957 & 4.776 & 0.98029 \\ Difference/\% & 0.3489 & \(-\)0.4179 & 0.3559 & 0.00698 \\ \hline \end{tabular}
\end{table}
Table 1: The integral scattering parameters calculated by the IIM and EBCM T-Matrix methods for the small spheroidal particle.  
Similar to Section 3.1, the integral scattering parameters of the large spheroid of our model are also compared with those of EBCM, the results are presented in Table 2. As can be seen, a good consistency is achieved between the results obtained by different models. The relative differences of these parameters are all less than 0.5%, which indicates that the IIM T-Matrix method can simulate the scattering process of large particles accurately.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Model Type** & \(\mathbf{C_{ext}/\mu m^{2}}\) & \(\mathbf{C_{abs}/\mu m^{2}}\) & \(\mathbf{C_{scd}/\mu m^{2}}\) & \(\mathbf{\omega}\) \\ \hline EBCM & 165.918 & 13.18 & 152.739 & 0.9205 \\ IIM T-Matrix & 165.687 & 13.134 & 152.553 & 0.9207 \\ Difference/\% & 0.1394 & 0.3502 & 0.1219 & \(-\)0.0175 \\ \hline \end{tabular}
\end{table}
Table 2: The integral scattering parameters calculated by the IIM and EBCM T-Matrix methods for the large spheroidal particle.  
Figure 5: The scattering phase matrix obtained by the IIM and EBCM T-Matrix methods for the large spheroid particle. The simulation errors of F\({}_{11}\) are denoted by relative errors. For F\({}_{12}\), F\({}_{34}\), and F\({}_{44}\), they are firstly normalized by F\({}_{11}\), and their simulation errors are evaluated by the absolute errors.